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Nsight Systems User Guide (PDF) - v2021.3.1 (older) - Last updated July 16, 2021 - Send Feedback -

## Nsight Systems User Guide

NVIDIA Nsight Systems user manual.

## 1. Profiling from the CLI

### 1.1. Installing the CLI on Your Target

The Nsight Systems CLI provides a simple interface to collect on a target without using the GUI. The collected data can then be copied to any system and analyzed later.

The CLI is distributed in the Target directory of the standard Nsight Systems download package. Users who want to install the CLI as a standalone tool can do so by copying the files within the Target directory. If you want the CLI output file (.qdstrm) to be auto-converted (to .qdrep) after the analysis is complete, you will need to copy the host directory as well.

If you wish to run the CLI without root (recommended mode), you will want to install in a directory where you have full access.

### 1.2. Command Line Options

The Nsight Systems command lines can have one of two forms:

    nsys [global_option]

or

    nsys [command_switch][optional command_switch_options][application] [optional application_options]

All command line options are case sensitive. For command switch options, when short options are used, the parameters should follow the switch after a space; e.g. `-s cpu`. When long options are used, the switch should be followed by an equal sign and then the parameter(s); e.g. `--sample=cpu`.

For this version of Nsight Systems, you must launch a process from the command line to begin analysis. If an instance of the requested process is already running when the CLI command is issued, the collection will fail. The launched process will be terminated when collection is complete unless the user specifies the --kill none option (details below).

The Nsight Systems CLI supports concurrent analysis by using sessions. Each Nsight Systems session is defined by a sequence of CLI commands that define one or more collections (e.g. when and what data is collected). A session begins with either a start, launch, or profile command. A session ends with a shutdown command, when a profile command terminates, or, if requested, when all the process tree(s) launched in the session exit. Multiple sessions can run concurrently on the same system.

A couple of notes about the use of paths in your command line.

- The Nsight Systems command line interface does not handle paths with spaces properly. Please use paths without spaces

- If you run a command (like `python X Y Z`) from a directory where the command is not located (like `/home/mystuff`), and the directory includes a sub-directory with the same name as the command (like `/home/mystuff/python`), the command line parser will interpret that as `"/home/mystuff/python X Y Z"`. This will not work because python, in this context, would reference the directory, not an executable. Please either run from the command's home directory or use the full path to the command.

### 1.2.1. CLI Global Options

Short | Long | Description
--- | --- | ---
-h | --help | Help message providing information about available command switches and their options.
-v | --version | Output Nsight Systems CLI version information.

### 1.3. CLI Command Switches

The Nsight Systems command line interface can be used in two modes. You may launch your application and begin analysis with options specified to the `nsys profile` command. Alternatively, you can control the launch of an application and data collection using interactive CLI commands.

Command | Description
--- | ---
profile | A fully formed profiling description requiring and accepting no further input. The command switch options used (see below table) determine when the collection starts, stops, what collectors are used (e.g. API trace, IP sampling, etc.), what processes are monitored, etc.
start | Start a collection in interactive mode. The start command can be executed before or after a launch command.
stop | Stop a collection that was started in interactive mode. When executed, all active collections stop, the CLI process terminates but the application continues running.
cancel | Cancels an existing collection started in interactive mode. All data already collected in the current collection is discarded.
launch | In interactive mode, launches an application in an environment that supports the requested options. The launch command can be executed before or after a start command.
shutdown | Disconnects the CLI process from the launched application and forces the CLI process to exit. If a collection is pending or active, it is cancelled
export | Generates an export file from an existing .qdrep file. For more information about the exported formats see the /documentation/nsys-exporter directory in your Nsight Systems installation directory.
stats | Post process existing Nsight Systems result, either in .qdrep or SQLite format, to generate statistical information.
analyze | Post process existing Nsight Systems result, either in .qdrep or SQLite format, to generate expert systems report.
status | Reports on the status of a CLI-based collection or the suitability of the profiing environment.
sessions | Gives information about all sessions running on the system.
nvprof | Special option to help with transition from legacy NVIDIA nvprof tool. Calling `nsys nvprof [options]` will provide the best available translation of `nvprof [options]` See Migrating from NVIDIA nvprof topic for details. No additional functionality of nsys will be available when using this option. Note: Not available on IBM Power targets.

### 1.3.1. CLI Profile Command Switch Options

After choosing the `profile` command switch, the following options are available. Usage:

    nsys [global-options] profile [options] <application> [application-arguments]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---

-t

--trace

cublas, cuda, cudnn, nvtx, opengl, openacc, openmp, osrt, mpi, vulkan, vulkan-annotations, opengl-annotations, dx11-annotations, dx12-annotations, oshmem, ucx, none

cuda, opengl, nvtx, osrt

Select the API(s) to be traced. The osrt switch controls the OS runtime libraries tracing. Multiple APIs can be selected, separated by commas only (no spaces). Since OpenACC, cuDNN and cuBLAS APIs are tightly linked with CUDA, selecting one of those APIs will automatically enable CUDA tracing. See information on --mpi-impl option below if mpi is selected. If the none option is selected, no APIs are traced and no other API can be selected. Note: cublas, cudnn, opengl, and vulkan are not available on IBM Power target.

| --mpi-impl | openmpi,mpich | openmpi | When using --trace=mpi to trace MPI APIs use --mpi-impl to specify which MPI implementation the application is using. If you are using a different MPI implementation, see Tracing MPI API calls section below. Calling --mpi-impl without --trace=mpi is not supported.
-s | --sample | cpu, none | cpu | Select whether or not to collect CPU samples. If none is selected, sampling is disabled. Note: Thread scheduling information will still be collected unless --cpuctxsw switch is set to none.
| --cpuctxsw | process-tree, none | process-tree | Trace OS thread scheduling activity. Select 'none' to disable tracing CPU context switches.

--sampling-period

integers between 4000000 and 125000

1000000

The number of CPU Instructions Retired events counted before a CPU instruction pointer (IP) sample is collected. If configured, call stacks may also be collected. The smaller the sampling period, the higher the sampling rate. Note that lower sampling periods will increase overhead and significantly increase the size of the result file(s). This option is only supported for Linux targets.

| --sampling-frequency | integers between 100 and 8000 | 1000 | Specify the sampling/backtracing frequency. The minimum supported frequency is 100 Hz. The maximum supported frequency is 8000 Hz. This option is supported only for QNX, Linux for Tegra, and Windows targets.
| --sampling-trigger | timer, sched, perf, cuda | timer,sched | Specify backtrace collection trigger. Multiple APIs can be selected, separated by commas only (no spaces). Available in Nsight Systems Embedded Platforms Edition only.
-b | --backtrace | fp,lbr,dwarf,none | lbr | Select the backtrace method to use while sampling. The option lbr uses Intel(c) Corporation's Last Branch Records, available only with Intel(c) CPUs codenamed Haswell and later. The option fp is frame pointer and assumes that frame pointers were enabled during compilation. The option dwarf uses DWARF's CFI (Call Frame Information).
| --command-file | < filename > | none | Open a file that contains profile switches and parse the switches. Note additional switches on the command line will override switches in the file. This flag can be specified more than once.
-y | --delay | < seconds > | 0 | Collection start delay in seconds.
-d | --duration | < seconds > | NA | Collection duration in seconds, duration must be greater than zero. Note that the profiler does not detach from the application, it lives until application termination.
-e | --env-var | A=B | NA | Set environment variable(s) for the application process to be launched. Environment variables should be defined as A=B. Multiple environment variables can be specified as A=B,C=D.
| --etw-provider | "<name>,<guid>", or path to JSON file | none | Add custom ETW trace provider(s). If you want to specify more attributes than Name and GUID, provide a JSON configuration file as as outlined below. This switch can be used multiple times to add multiple providers. Note: Only available for Windows targets.
| --osrt-threshold | < nanoseconds > | 1000 ns | Set the minimum time that a OS Runtime event must take before it is collected. Setting this value too low can cause high application overhead and seriously increase the size of your results file. Note: Not available for IBM Power targets.
| --osrt-backtrace-depth | integrer | 24 | Set the depth for the backtraces collected for OS runtime libraries calls.
| --osrt-backtrace-threshold | nanoseconds | 80000 | Set the duration, in nanoseconds, that all OS runtime libraries calls must execute before backtraces are collected.

--cudabacktrace

all, none, kernel, memory, sync, other

none

When tracing CUDA APIs, enable the collection of a backtrace when a CUDA API is invoked. Significant runtime overhead may occur. Values may be combined using ','. Each value except 'none' may be appended with a threshold after ':'. Threshold is duration, in nanoseconds, that CUDA APIs must execute before backtraces are collected, e.g. 'kernel:500'. Default value for each threshold is 1000ns (1us). Note: CPU sampling must be enabled. Note: Not available on IBM Power targets.

--cuda-flush-interval

milliseconds

0

Set the interval, in milliseconds, when buffered CUDA data is automatically saved to storage. Immediately before data is saved to storage, a cudaDeviceSynchonize call is inserted into the workflow which will cause application overhead. If data is not periodically saved, nsys will dynamically allocate memory as needed to store data during collection. For collections over 30 seconds an interval of 10 seconds is recommended.

| --cuda-memory-usage | true, false | false | Track the GPU memory usage by CUDA kernels. Applicable only when CUDA tracing is enabled. Note: This feature may cause significant runtime overhead.
| --cuda-um-cpu-page-faults | true, false | false | This switch tracks the page faults that occur when CPU code tries to access a memory page that resides on the device. Note that this feature may cause significant runtime overhead.
| --cuda-um-gpu-page-faults | true, false | false | This switch tracks the page faults that occur when GPU code tries to access a memory page that resides on the host. Note that this feature may cause significant runtime overhead.

-o

--output

< filename >

report#

Set report file name. Any %q{ENV_VAR} pattern in the filename will be substituted with the value of the environment variable. Any %h pattern in the filename will be substituted with the hostname of the system. Any %p pattern in the filename will be substituted with the PID of the target process or the PID of the root process if there is a process tree. Any %% pattern in the filename will be substituted with %. Default is report#.{qdstrm,qdrep,sqlite} in the working directory.

| --export | sqlite, none | none | Create additional output file(s) based on the data collected. Current options are sqlite or none. WARNING: If the collection captures a large amount of data, creating the database file may take several minutes to complete.
| --stats | true, false | false | Generate summary statistics after the collection. WARNING: When set to true, an SQLite database will be created after the collection. If the collection captures a large amount of data, creating the database file may take several minutes to complete.
-f | --force-overwrite | true, false | false | If true, overwrite all existing result files with same output filename (.qdstrm,.qdrep, .sqlite)
-w | --show-output | true, false | true | If true, send target process’ stdout and stderr streams to the console.
-n | --inherit-environment | true, false | true | When true, the current environment variables and the tool’s environment variables will be specified for the launched process. When false, only the tool’s environment variables will be specified for the launched process.
-x | --stop-on-exit | true, false | true | If true, stop collecting automatically when the launched process has exited or when the duration expires - whichever occurs first. If false, duration must be set and the collection stops only when the duration expires. Nsight Systems does not officially support runs longer than 5 minutes.
| --wait | primary,all | all | If primary, the CLI will wait on the application process termination. If all, the CLI will additionally wait on re-parented processes created by the application.
| --trace-fork-before-exec | true, false | false | If true, trace any child process after fork and before they call one of the exec functions. Beware, tracing in this interval relies on undefined behavior and might cause your application to crash or deadlock.
-c | --capture-range | none, cudaProfilerApi, hotkey, nvtx | none | When --capture-range is used, profiling will start only when appropriate start API or hotkey is invoked. If --capture-range is set to none, start/stop API calls and hotkeys will be ignored. Note: hotkey works for graphic applications only.

--capture-range-end

none, stop, stop-shutdown, repeat[:N], repeat-shutdown:N

stop-shutdown

Specify the desired behavior when a capture range ends. Applicable only when used along with --capture-range option. If `none`, capture range end will be ignored. If `stop`, collection will stop at capture range end. Any subsequent capture ranges will be ignored. Target app will continue running. If `stop-shutdown`, collection will stop at capture range end and session will be shutdown. If `repeat[:N]`, collection will stop at capture range end and subsequent capture ranges will trigger more collections. Use the optional `:N` to specify max number of capture ranges to be honored. Any subsequent capture ranges will be ignored once N capture ranges are collected. If `repeat-shutdown:N`, same behavior as `repeat:N` but session will be shutdown after N ranges. For `stop-shutdown` and `repeat-shutdown:N`, use --kill option to specify whether target app should be terminated when shutting down session.

| --stop-on-range-end | true,false | true | Stop profiling when the capture range ends. Applicable only when used along with --capture-range option. WARNING: This switch has been deprecated and will be removed in a future version.
-p | --nvtx-capture | range@domain,range,range@ |  | Specify NVTX capture range. See below for details. This option is applicable only when used along with --capture-range=nvtx.
| --ftrace |  |  | Collect ftrace events. Argument should list events to collect as: subsystem1/event1,subsystem2/event2. Requires root. No ftrace events are collected by default. Note: Not available on IBM Power targets.
| --ftrace-keep-user-config |  |  | Skip initial ftrace setup and collect already configured events. Default resets the ftrace configuration.
| --vsync | true, false | false | Collect vsync events. If collection of vsync events is enabled, display/display_scanline ftrace events will also be captured.
| --dx-force-declare-adapter-removal-support | true, false | false | The Nsight Systems trace initialization involves creating a D3D device and discarding it. Enabling this flag makes a call to DXGIDeclareAdapterRemovalSupport() before device creation. Requires DX11 or DX12 trace to be enabled.
| --gpuctxsw | true,false | false | Trace GPU context switches. Note that this requires driver r435.17 or later and root permission. Not available on IBM Power targets.
| --gpu-metrics-device | GPU ID, help, none | none | Collect GPU Metrics from specified devices. Determine GPU IDs by using `--gpu-metrics-device=help` switch.
| --gpu-metrics-frequency | integer | 10000 | Specify GPU Metrics sampling frequency. Minimum supported frequency is 10 (Hz). Maximum supported frequency is 200000(Hz).
| --gpu-metrics-set | index | first | Specify metric set for GPU Metrics sampling. The argument must be one of indices reported by `--gpu-metrics-set=help` switch. Default is the first metric set that supports selected GPU.
| --kill | none, sigkill, sigterm, signal number | sigterm | Send signal to the target application's process group.

--session-new

[a-Z][0-9,a-Z,spaces]

profile-<id>-<application>

Name the session created by the command. Name must start with an alphabetical character followed by printable or space characters. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.

| --retain-etw-files | true, false | false | If true, retains ETW files generated by the trace, merges and moves the files to the output directory.
| --opengl-gpu-workload | true, false | true | If true, trace the OpenGL workloads's GPU activity. Note that this switch is applicable only when --trace=opengl is specified. This option is not supported on IBM Power targets.
| --vulkan-gpu-workload | true, false | true | If true, trace the Vulkan workloads's GPU activity. Note that this switch is applicable only when --trace=vulkan is specified. This option is not supported on QNX.
| --dx12-gpu-workload | true, false | true | If true, trace the DX12 workloads's GPU activity. Note that this switch is applicable only when --trace=dx12 is specified. This option is only supported on Windows targets.
| --dx12-wait-calls | true, false | true | If true, trace wait calls that block on fences for DX12. Note that this switch is applicable only when --trace=dx12 is specified. This option is only supported on Windows targets.
| --wddm-additional-events | true, false | false | If true, collect additional range of ETW events, including context status, allocations, sync wait and signal events, etc. Note that this switch is applicable only when --trace=wddm is specified. This option is only supported on Windows targets.
| --hotkey-capture | 'F1' to 'F12' | 'F12' | Hotkey to trigger the profiling session. Note that this switch is applicable only when --capture-range=hotkey is specified.
| --cpu-core-events | 0x11,0x13,...,none | %s | Collect per-core PMU counters. Multiple values can be selected, separated by commas only (no spaces). Use the --cpu-core-events=help switch to see the full list of values. Available in Nsight Systems Embedded Platforms Edition only.
| --cpu-cluster-events | 0x16, 0x17, ..., none | none | Collect per-cluster Uncore PMU counters. Multiple values can be selected, separated by commas only (no spaces). Use the --cpu-cluster-events=help switch to see the full list of values. Available in Nsight Systems Embedded Platforms Edition only.
| --cpu-socket-events | 0x2a, 0x2c, ..., none | none | Collect per-socket Uncore PMU counters. Multiple values can be selected, separated by commas only (no spaces). Use the --cpu-cluster-events=help switch to see the full list of values. Available in Nsight Systems Embedded Platforms Edition only.
| --process-scope | main, process-tree, system-wide | main | Select which process(es) to trace. Available in Nsight Systems Embedded Platforms Edition only. Nsight Systems Workstation Edition will always trace system-wide in this version of the tool.
| --accelerator-trace | none, nvmedia | none | Collect other accelerators workload trace from the hardware engine units. Available in Nsight Systems Embedded Platforms Edition only.
| --clock-frequency-changes | true, false | false | Collect clock frequency changes. Available in Nsight Systems Embedded Platforms Edition only.
| --xhv-trace | < filepath pct.json > | none | Collect hypervisor trace. Available in Nsight Systems Embedded Platforms Edition only.

### 1.3.2. CLI Start Command Switch Options

After choosing the `start` command switch, the following options are available. Usage:

    nsys [global-options] start [options]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
-c | --capture-range | none, cudaProfilerApi, hotkey, nvtx | none | When --capture-range is used, profiling will start only when appropriate start API or hotkey is invoked. If --capture-range is set to none, start/stop API calls and hotkeys will be ignored. Note: hotkey works for graphic applications only.

-o

--output

< filename >

report#

Set report file name. Any %q{ENV_VAR} pattern in the filename will be substituted with the value of the environment variable. Any %h pattern in the filename will be substituted with the hostname of the system. Any %p pattern in the filename will be substituted with the PID of the target process or the PID of the root process if there is a process tree. Any %% pattern in the filename will be substituted with %. Default is report#.{qdstrm,qdrep,sqlite} in the working directory.

| --export | sqlite, hdf, text, json, none | none | Create additional output file(s) based on the data collected. WARNING: If the collection captures a large amount of data, creating the export file may take several minutes to complete.
| --stats | true, false | false | Generate summary statistics after the collection. WARNING: When set to true, an SQLite database will be created after the collection. If the collection captures a large amount of data, creating the database file may take several minutes to complete.
-f | --force-overwrite | true, false | false | If true, overwrite all existing result files with same output filename (.qdstrm,.qdrep, .sqlite)
-x | --stop-on-exit | true, false | true | If true, stop collecting automatically when all tracked processes have exited or when `stop` command is issued - whichever occurs first. If false, stop only on `stop` command. Note: When this is true, `stop` command is optional. Nsight Systems does not officially support runs longer than 5 minutes.

--capture-range-end

none, stop, stop-shutdown, repeat[:N], repeat-shutdown:N

stop-shutdown

Specify the desired behavior when a capture range ends. Applicable only when used along with --capture-range option. If `none`, capture range end will be ignored. If `stop`, collection will stop at capture range end. Any subsequent capture ranges will be ignored. Target app will continue running. If `stop-shutdown`, collection will stop at capture range end and session will be shutdown. If `repeat[:N]`, collection will stop at capture range end and subsequent capture ranges will trigger more collections. Use the optional `:N` to specify max number of capture ranges to be honored. Any subsequent capture ranges will be ignored once N capture ranges are collected. If `repeat-shutdown:N`, same behavior as `repeat:N` but session will be shutdown after N ranges. For `stop-shutdown` and `repeat-shutdown:N`, use --kill option to specify whether target app should be terminated when shutting down session.

| --stop-on-range-end | true,false | true | Stop profiling when the capture range ends. Applicable only when used along with --capture-range option. WARNING: This switch has been deprecated and will be removed in a future version.
| --etw-provider | "<name>,<guid>", or path to JSON file | none | Add custom ETW trace provider(s). If you want to specify more attributes than Name and GUID, provide a JSON configuration file as as outlined below. This switch can be used multiple times to add multiple providers. Note: Only available for Windows targets.
| --dx-force-declare-adapter-removal-support | true, false | false | The Nsight Systems trace initialization involves creating a D3D device and discarding it. Enabling this flag makes a call to DXGIDeclareAdapterRemovalSupport() before device creation. Requires DX11 or DX12 trace to be enabled.
| --ftrace |  |  | Collect ftrace events. Argument should list events to collect as: subsystem1/event1,subsystem2/event2. Requires root. No ftrace events are collected by default. Note: Not supported on IBM Power targets.
| --ftrace-keep-user-config |  |  | Skip initial ftrace setup and collect already configured events. Default resets the ftrace configuration.
| --gpu-metrics-device | GPU ID, help, none | none | Collect GPU Metrics from specified devices. Determine GPU IDs by using `--gpu-metrics-device=help` switch.
| --gpu-metrics-frequency | integer | 10000 | Specify GPU Metrics sampling frequency. Minimum supported frequency is 10 (Hz). Maximum supported frequency is 200000(Hz).
| --gpu-metrics-set | index | first | Specify metric set for GPU Metrics sampling. The argument must be one of indices reported by `--gpu-metrics-set=help` switch. Default is the first metric set that supports selected GPU.
| --gpuctxsw | true,false | false | Trace GPU context switches. Note that this requires driver r435.17 or later and root permission. Not supported on IBM Power targets.
| --session | session identifier | none | Start the application in the indicated session. The option argument must represent a valid session name or ID as reported by `nsys sessions list`. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.
| --session-new | [a-Z][0-9,a-Z,spaces] | [default] | Start the application in a new session. Name must start with an alphabetical character followed by printable or space characters. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.
| --vsync | true, false | false | Collect vsync events. If collection of vsync events is enabled, display/display_scanline ftrace events will also be captured.
| --process-scope | main, process-tree, system-wide | main | Select which process(es) to trace. Available in Nsight Systems Embedded Platforms Edition only. Nsight Systems Workstation Edition will always trace system-wide in this version of the tool.
| --accelerator-trace | none, nvmedia | none | Collect other accelerators workload trace from the hardware engine units. Available in Nsight Systems Embedded Platforms Edition only.
| --clock-frequency-changes | true, false | false | Collect clock frequency changes. Available in Nsight Systems Embedded Platforms Edition only.
| --xhv-trace | < filepath pct.json > | none | Collect hypervisor trace. Available in Nsight Systems Embedded Platforms Edition only.

### 1.3.3. CLI Stop Command Switch Options

After choosing the `stop` command switch, the following options are available. Usage:

    nsys [global-options] stop [options]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
| --session | session identifier | none | Stop the indicated session. The option argument must represent a valid session name or ID as reported by `nsyssessions list`. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.

### 1.3.4. CLI Cancel Command Switch Options

After choosing the `cancel` command switch, the following options are available. Usage:

    nsys [global-options] cancel [options]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
| --session | session identifier | none | Cancel the indicated session. The option argument must represent a valid session name or ID as reported by `nsyssessions list`. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.

### 1.3.5. CLI Launch Command Switch Options

After choosing the `launch` command switch, the following options are available. Usage:

    nsys [global-options] launch [options] <application> [application-arguments]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---

-t

--trace

cublas, cuda, cudnn, nvtx, opengl, openacc, openmp, osrt, mpi, vulkan, vulkan-annotations, opengl-annotations, dx11-annotations, dx12-annotations, oshmem, ucx, none

cuda, opengl, nvtx, osrt

Select the API(s) to be traced. The osrt switch controls the OS runtime libraries tracing. Multiple APIs can be selected, separated by commas only (no spaces). Since OpenACC, cuDNN and cuBLAS APIs are tightly linked with CUDA, selecting one of those APIs will automatically enable CUDA tracing. See information on --mpi-impl option below if mpi is selected. If the none option is selected, no APIs are traced and no other API can be selected. Note: cublas, cudnn, opengl, and vulkan are not available on IBM Power target.

| --mpi-impl | openmpi,mpich | openmpi | When using --trace=mpi to trace MPI APIs use --mpi-impl to specify which MPI implementation the application is using. If you are using a different MPI implementation, see Tracing MPI API calls section below. Calling --mpi-impl without --trace=mpi is not supported.
-s | --sample | cpu, none | cpu | Select whether or not to collect CPU samples. If none is selected, sampling is disabled. Note: Thread scheduling information will still be collected unless --cpuctxsw switch is set to none.
| --cpuctxsw | process-tree, none | process-tree | Trace OS thread scheduling activity. Select 'none' to disable tracing CPU context switches.

--sampling-period

integers between 4000000 and 125000

1000000

The number of CPU Instructions Retired events counted before a CPU instruction pointer (IP) sample is collected. If configured, call stacks may also be collected. The smaller the sampling period, the higher the sampling rate. Note that lower sampling periods will increase overhead and significantly increase the size of the result file(s). This option is available only on Linux targets.

| --sampling-frequency | integers between 100 and 8000 | 1000 | Specify the sampling/backtracing frequency. The minimum supported frequency is 100 Hz. The maximum supported frequency is 8000 Hz. This option is supported only on QNX, Linux for Tegra, and Windows targets.
-b | --backtrace | fp,lbr,dwarf,none | lbr | Select the backtrace method to use while sampling. The option lbr uses Intel(c) Corporation's Last Branch Records, available only with Intel(c) CPUs codenamed Haswell and later. The option fp is frame pointer and assumes that frame pointers were enabled during compilation. The option dwarf uses DWARF's CFI (Call Frame Information).
| --command-file | < filename > | none | Open a file that contains launch switches and parse the switches. Note additional switches on the command line will override switches in the file. This flag can be specified more than once.
-e | --env-var | A=B | NA | Set environment variable(s) for the application process to be launched. Environment variables should be defined as A=B. Multiple environment variables can be specified as A=B,C=D.
| --etw-provider | "<name>,<guid>", or path to JSON file | none | Add custom ETW trace provider(s). If you want to specify more attributes than Name and GUID, provide a JSON configuration file as as outlined below. This switch can be used multiple times to add multiple providers. Note: Only available for Windows targets.
| --osrt-threshold | < nanoseconds > | 1000 ns | Set the minimum time that a OS Runtime event must take before it is collected. Setting this value too low can cause high application overhead and seriously increase the size of your results file. Note: Not available for IBM Power targets.
| --osrt-backtrace-depth | integrer | 24 | Set the depth for the backtraces collected for OS runtime libraries calls.
| --osrt-backtrace-threshold | nanoseconds | 80000 | Set the duration, in nanoseconds, that all OS runtime libraries calls must execute before backtraces are collected.

--cudabacktrace

all, none, kernel, memory, sync, other

none

When tracing CUDA APIs, enable the collection of a backtrace when a CUDA API is invoked. Significant runtime overhead may occur. Values may be combined using ','. Each value except 'none' may be appended with a threshold after ':'. Threshold is duration, in nanoseconds, that CUDA APIs must execute before backtraces are collected, e.g. 'kernel:500'. Default value for each threshold is 1000ns (1us). Note: CPU sampling must be enabled. Note: Not available on IBM Power targets.

--cuda-flush-interval

milliseconds

0

Set the interval, in milliseconds, when buffered CUDA data is automatically saved to storage. Immediately before data is saved to storage, a cudaDeviceSynchonize call is inserted into the workflow which will cause application overhead. If data is not periodically saved, nsys will dynamically allocate memory as needed to store data during collection. For collections over 30 seconds an interval of 10 seconds is recommended.

| --cuda-memory-usage | true, false | false | Track the GPU memory usage by CUDA kernels. Applicable only when CUDA tracing is enabled. Note: This feature may cause significant runtime overhead.
| --cuda-um-cpu-page-faults | true, false | false | This switch tracks the page faults that occur when CPU code tries to access a memory page that resides on the device. Note that this feature may cause significant runtime overhead.
| --cuda-um-gpu-page-faults | true, false | false | This switch tracks the page faults that occur when GPU code tries to access a memory page that resides on the host. Note that this feature may cause significant runtime overhead.
-w | --show-output | true, false | true | If true, send target process’ stdout and stderr streams to the console
-n | --inherit-environment | true, false | true | When true, the current environment variables and the tool’s environment variables will be specified for the launched process. When false, only the tool’s environment variables will be specified for the launched process.
-p | --nvtx-capture | message@idomain | none | Specify NVTX capture range. See below for details.
| --trace-fork-before-exec | true, false | false | If true, trace any child process after fork and before they call one of the exec functions. Beware, tracing in this interval relies on undefined behavior and might cause your application to crash or deadlock.
| --wait | primary,all | all | If primary, the CLI will wait on the application process termination. If all, the CLI will additionally wait on re-parented processes created by the application.
| --session | session identifier | none | Launch the application in the indicated session. The option argument must represent a valid session name or ID as reported by `nsys sessions list`. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.
| --session-new | [a-Z][0-9,a-Z,spaces] | [default] | Launch the application in a new session. Name must start with an alphabetical character followed by printable or space characters. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.
| --opengl-gpu-workload | true, false | true | If true, trace the OpenGL workloads's GPU activity. Note that this switch is applicable only when --trace=opengl is specified. This option is not supported on IBM Power targets.
| --vulkan-gpu-workload | true, false | true | If true, trace the Vulkan workloads's GPU activity. Note that this switch is applicable only when --trace=vulkan is specified. This option is not supported on QNX.
| --dx12-gpu-workload | true, false | true | If true, trace the DX12 workloads's GPU activity. Note that this switch is applicable only when --trace=dx12 is specified. This option is only supported on Windows targets.
| --dx12-wait-calls | true, false | true | If true, trace wait calls that block on fences for DX12. Note that this switch is applicable only when --trace=dx12 is specified. This option is only supported on Windows targets.
| --wddm-additional-events | true, false | false | If true, collect additional range of ETW events, including context status, allocations, sync wait and signal events, etc. Note that this switch is applicable only when --trace=wddm is specified. This option is only supported on Windows targets.
| --hotkey-capture | 'F1' to 'F12' | 'F12' | Hotkey to trigger the profiling session. Note that this switch is applicable only when --capture-range=hotkey is specified.
| --cpu-core-events | 0x11,0x13,...,none | %s | Collect per-core PMU counters. Multiple values can be selected, separated by commas only (no spaces). Use the --cpu-core-events=help switch to see the full list of values. Available in Nsight Systems Embedded Platforms Edition only.
| --cpu-cluster-events | 0x16, 0x17, ..., none | none | Collect per-cluster Uncore PMU counters. Multiple values can be selected, separated by commas only (no spaces). Use the --cpu-cluster-events=help switch to see the full list of values. Available in Nsight Systems Embedded Platforms Edition only.
| --cpu-socket-events | 0x2a, 0x2c, ..., none | none | Collect per-socket Uncore PMU counters. Multiple values can be selected, separated by commas only (no spaces). Use the --cpu-cluster-events=help switch to see the full list of values. Available in Nsight Systems Embedded Platforms Edition only.

### 1.3.6. CLI Shutdown Command Switch Options

After choosing the `shutdown` command switch, the following options are available. Usage:

    nsys [global-options] shutdown [options]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
| --kill | none, sigkill, sigterm, signal number | sigterm | Send signal to the target application's process group.
| --session | session identifier | none | Shutdown the indicated session. The option argument must represent a valid session name or ID as reported by `nsys sessions list`. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.

### 1.3.7. CLI Export Command Switch Options

After choosing the `export` command switch, the following options are available. Usage:

    nsys [global-options] export [options] [qdrep-file]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
-o | --output | <filename> | <inputfile.ext> | Set the .output filename. The default is the .qdrep filename with the extension for the chosen format.
-t | --type | sqlite, hdr, text, json, info | sqlite | Export format type. HDF format is supported only on x86_64 Linux and Windows
-f | --force-overwrite | true, false | false | If true, overwrite existing result file
-l | --lazy | true, false | true | Controls if table creation is lazy or not. When true, a table will only be created when it contains data. This option will be deprecated in the future, and all exports will be non-lazy. This affects SQLite and HDF5 exports only.
-q | --quiet | true, false | false | If true, do not display progress bar
| --separate-strings | true,false | false | Output stored strings and thread names separately, with one value per line. This affects JSON and text output only.

### CLI Stats Switch Options

The `nsys stats` command generates a series of summary or trace reports. These reports can be output to the console, or to individual files, or piped to external processes. Reports can be rendered in a variety of different output formats, from human readable columns of text, to formats more appropriate for data exchange, such as CSV.

Reports are generated from an SQLite export of a .qdrep file. If a .qdrep file is specified, Nsight Systems will look for an accompanying SQLite file and use it. If no SQLite file exists, one will be exported and created.

Individual reports are generated by calling out to scripts that read data from the SQLite file and return their report data in CSV format. Nsight Systems ingests this data and formats it as requested, then displays the data to the console, writes it to a file, or pipes it to an external process. Adding new reports is as simple as writing a script that can read the SQLite file and generate the required CSV output. See the shipped scripts as an example. Both reports and formatters may take arguments to tweak their processing. For details on shipped scripts and formatters, see Report Scripts topic.

Reports are processed using a three-tuple that consists of 1) the requested report (and any arguments), 2) the presentation format (and any arguments), and 3) the output (filename, console, or external process). The first report specified uses the first format specified, and is presented via the first output specified. The second report uses the second format for the second output, and so forth. If more reports are specified than formats or outputs, the format and/or output list is expanded to match the number of provided reports by repeating the last specified element of the list (or the default, if nothing was specified).

`nsys stats` is a very powerful command and can handle complex argument structures, please see the topic below on Example Stats Command Sequences.

After choosing the `stats` command switch, the following options are available. Usage:

`nsys [global-options] stats [options] [input-file]`

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
| --help-reports | <report_name>, ALL, [none] | none | With no argument, give a summary of the available summary and trace reports. If a report name is given, a more detailed explanation of the report is displayed. If `ALL` is given, a more detailed explanation of all available reports is displayed.
| --help-formats | <format_name>, ALL, [none] | none | With no argument, give a summary of the available output formats. If a format name is given, a more detailed explanation of that format is displayed. If `ALL` is given, a more detailed explanation of all available formats is displayed.
| --sqlite | <file.sqlite> |  | Specify the SQLite export filename. If this file exists, it will be used. If this file doesn't exist (or if --force-export was given) this file will be created from the specified .qdrep file before report processing. This option cannot be used if the specified input file is also an SQLite file.

-r

--report

See Report Scripts

Specify the report(s) to generate, including any arguments. This option may be used multiple times. Multiple reports may also be specified using a comma-separated list (<name[:args...][,name[:args...]...]>). If no reports are specified, the following will be used as the default report set: cudaapisum, gpukernsum, gpumemtimesum, gpumemsizesum, osrtsum, nvtxppsum, openmpevtsum. See Report Scripts section for details about existing built-in scripts and how to make your own.

-f

--format

column, table, csv, tsv, json, hdoc, htable, .

Specify the output format of the corresponding report(s). The special name "." indicates the default format for the given output. The default format for console is column, while files and process outputs default to csv. This option may be used multiple times. Multiple formats may also be specified using a comma-separated list (<name[:args...][,name[:args...]...]>). See Report Scripts for options available with each format.

-o

--output

-, @<command>, <basename>, .

-

Specify the output mechanism for the corresponding reports(s). There are three output mechanisms: print to console (-), output to command (@<command>), or output to file (<basename>). The option "." can be used to specify using the default basefile, which is the basename of the input file. The filename used will be <basename>_<report&args>.<output_format>.

--report-dir

Add a directory to the path used to find report scripts. This is usually only needed if you have one or more directories with personal scripts. This option may be used multiple times. Each use adds a new directory to the end of the path. The last two entries in the path will always be the current working directory, followed by the directory containing the shipped `nsys` reports.

| --force-export | true, false | false | Force a re-export of the SQLite file from the specified .qdrep file, even if an SQLite file already exists.
| --force-overwrite | true, false | false | Overwrite any existing report file(s).
-q | --quiet |  |  | Only display errors.

### CLI Analyze Switch Options

The `nsys analyze` command generates and outputs to the terminal a report using expert system rules on existing results. Reports are generated from an SQLite export of a .qdrep file. If a .qdrep file is specified, Nsight Systems will look for an accompanying SQLite file and use it. If no SQLite export file exists, one will be created.

After choosing the `analyze` command switch, the following options are available. Usage:

`nsys [global-options] analyze [options] [input-file]`

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
-h | --help |  |  | Print help message.
| --help-rules | <report_name>, ALL, [none] | none | With no argument, list available rules with a short description. If a rule name is given, a more detailed explanation of the rule is displayed. If `ALL` is given, a more detailed explanation of all available rules is displayed.
| --sqlite | <file.sqlite> |  | Specify the SQLite export filename. If this file exists, it will be used. If this file doesn't exist (or if --force-export was given) this file will be created from the specified .qdrep file before report processing. This option cannot be used if the specified input file is also an SQLite file.
-r | --rule | asyn-memcpy-pageable, sync-memcpy, sync-memset, sync-api, gpu-starvation, gpu-low-utilization | all | Specify the rules(s) to execute, including any arguments. This option may be used multiple times. Multiple reports may also be specified using a comma-separated list. See Expert Systems section for details on all rules.
| --force-export | true, false | false | Force a re-export of the SQLite file from the specified .qdrep file, even if an SQLite file already exists.
-q | --quiet |  |  | Do not display verbose messages.

### 1.3.10. CLI Status Command Switch Options

After choosing the `status` command switch, the following options are available. Usage:

    nsys [global-options] status [options]

Short | Long | Possible Parameters | Default | Switch Description
--- | --- | --- | --- | ---
| <none> |  |  | Returns current state of the CLI.
-e | --environment |  |  | Returns information about the system regarding suitability of the profiling environment.
| --session | session identifier | none | Print the status of the indicated session. The option argument must represent a valid session name or ID as reported by `nsyssessions list`. Any `%q{ENV_VAR}` pattern will be substituted with the value of the environment variable. Any `%h` pattern will be substituted with the hostname of the system. Any `%%` pattern will be substituted with `%`.

### 1.3.11. CLI Sessions Command Switch Subcommands

After choosing the `sessions` command switch, the following subcommands are available. Usage:

    nsys [global-options] sessions [subcommand]

Subcommand | Description
--- | ---
list | List all active sessions including ID, name, and state information

### 1.4. Example Single Command Lines

Version Information

    nsys -v

Effect: Prints tool version information to the screen.

Default analysis run

    nsys profile <application>
        [application-arguments]

Effect: Launch the application using the given arguments. Start collecting immediately and end collection when the application stops. Trace CUDA, OpenGL, NVTX, and OS runtime libraries APIs. Collect CPU sampling information and thread scheduling information. With Nsight Systems Embedded Platforms Edition this will only analysis the single process. With Nsight Systems Workstation Edition this will trace the process tree. Generate the report#.qdrep file in the default location, incrementing the report number if needed to avoid overwriting any existing output files.

Limited trace only run

    nsys profile --trace=cuda,nvtx -d 20
        --sample=none --cpuctxsw=none -o my_test <application>
        [application-arguments]

Effect: Launch the application using the given arguments. Start collecting immediately and end collection after 20 seconds or when the application ends. Trace CUDA and NVTX APIs. Do not collect CPU sampling information or thread scheduling information. Profile any child processes. Generate the output file as my_test.qdrep in the current working directory.

Delayed start run

    nsys profile -e TEST_ONLY=0 -y 20
        <application> [application-arguments]

Effect: Set environment variable TEST_ONLY=0. Launch the application using the given arguments. Start collecting after 20 seconds and end collection at application exit. Trace CUDA, OpenGL, NVTX, and OS runtime libraries APIs. Collect CPU sampling and thread schedule information. Profile any child processes. Generate the report#.qdrep file in the default location, incrementing if needed to avoid overwriting any existing output files.

Collect ftrace events

    nsys profile --ftrace=drm/drm_vblank_event
        -d 20

Effect: Collect ftrace `drm_vblank_event` events for 20 seconds. Generate the report#.qdrep file in the current working directory. Note that ftrace event collection requires running as root. To get a list of ftrace events available from the kernel, run the following:

    sudo cat /sys/kernel/debug/tracing/available_events

Run GPU metric sampling on one TU10x

    nsys profile --gpu-metrics-device=0
    	--gpu-metrics-set=tu10x-gfxt <application>

Effect: Launch application. Collect default options and GPU metrics for the first GPU (a TU10x), using the tu10x-gfxt metric set at the default frequency (10 kHz). Profile any child processes. Generate the report#.qdrep file in the default location, incrementing if needed to avoid overwriting any existing output files.

Run GPU metric sampling on all GPUs at a set frequency

    nsys profile --gpu-metrics-device=all
    	--gpu-metrics-frequency=20000 <application>

Effect: Launch application. Collect default options and GPU metrics for all available GPUs using the first suitable metric set for each and sampling at 20 kHz. Profile any child processes. Generate the report#.qdrep file in the default location, incrementing if needed to avoid overwriting any existing output files.

Collect custom ETW trace using configuration file

    nsys profile --etw-provider=file.JSON

Effect: Configure custom ETW collectors using the contents of file.JSON. Collect data for 20 seconds. Generate the report#.qdrep file in the current working directory.

A template JSON configuration file is located at in the Nsight Systems installation directory as \target-windows-x64\etw_providers_template.json. This path will show up automatically if you call

    nsys profile --help

The level attribute can only be set to one of the following:

- TRACE_LEVEL_CRITICAL
- TRACE_LEVEL_ERROR
- TRACE_LEVEL_WARNING
- TRACE_LEVEL_INFORMATION
- TRACE_LEVEL_VERBOSE

The flags attribute can only be set to one or more of the following:

- EVENT_TRACE_FLAG_ALPC
- EVENT_TRACE_FLAG_CSWITCH
- EVENT_TRACE_FLAG_DBGPRINT
- EVENT_TRACE_FLAG_DISK_FILE_IO
- EVENT_TRACE_FLAG_DISK_IO
- EVENT_TRACE_FLAG_DISK_IO_INIT
- EVENT_TRACE_FLAG_DISPATCHER
- EVENT_TRACE_FLAG_DPC
- EVENT_TRACE_FLAG_DRIVER
- EVENT_TRACE_FLAG_FILE_IO
- EVENT_TRACE_FLAG_FILE_IO_INIT
- EVENT_TRACE_FLAG_IMAGE_LOAD
- EVENT_TRACE_FLAG_INTERRUPT
- EVENT_TRACE_FLAG_JOB
- EVENT_TRACE_FLAG_MEMORY_HARD_FAULTS
- EVENT_TRACE_FLAG_MEMORY_PAGE_FAULTS
- EVENT_TRACE_FLAG_NETWORK_TCPIP
- EVENT_TRACE_FLAG_NO_SYSCONFIG
- EVENT_TRACE_FLAG_PROCESS
- EVENT_TRACE_FLAG_PROCESS_COUNTERS
- EVENT_TRACE_FLAG_PROFILE
- EVENT_TRACE_FLAG_REGISTRY
- EVENT_TRACE_FLAG_SPLIT_IO
- EVENT_TRACE_FLAG_SYSTEMCALL
- EVENT_TRACE_FLAG_THREAD
- EVENT_TRACE_FLAG_VAMAP
- EVENT_TRACE_FLAG_VIRTUAL_ALLOC

Typical case: profile a Python script that uses CUDA

    nsys profile --trace=cuda,cudnn,cublas,osrt,nvtx
        --delay=60 python my_dnn_script.py

Effect: Launch a Python script and start profiling it 60 seconds after the launch, tracing CUDA, cuDNN, cuBLAS, OS runtime APIs, and NVTX as well as collecting thread schedule information.

Typical case: profile an app that uses Vulkan

    nsys profile --trace=vulkan,osrt,nvtx
        --delay=60 ./myapp

Effect: Launch an app and start profiling it 60 seconds after the launch, tracing Vulkan, OS runtime APIs, and NVTX as well as collecting CPU sampling and thread schedule information.

### 1.5. Example Interactive CLI Command Sequences

Collect from beginning of application, end manually

    nsys start --stop-on-exit=false
    nsys launch --trace=cuda,nvtx --sample=none <application> [application-arguments]
    nsys stop

Effect: Create interactive CLI process and set it up to begin collecting as soon as an application is launched. Launch the application, set up to allow tracing of CUDA and NVTX as well as collection of thread schedule information. Stop only when explicitly requested. Generate the report#.qdrep in the default location.

> Note:

> If you start a collection and fail to stop the collection (or if you are allowing it to stop on exit, and the application runs for too long) your system’s storage space may be filled with collected data causing significant issues for the system. Nsight Systems will collect a different amount of data/sec depending on options, but in general Nsight Systems does not support runs of more than 5 minutes duration.

Run application, begin collection manually, run until process ends

    nsys launch -w true <application> [application-arguments]
    nsys start

Effect: Create interactive CLI and launch an application set up for default analysis. Send application output to the terminal. No data is collected until you manually start collection at area of interest. Profile until the application ends. Generate the report#.qdrep in the default location.

> Note: | If you launch an application and that application and any descendants exit before start is called Nsight Systems will create a fully formed .qdrep file containing no data.

Run application, start/stop collection using cudaProfilerStart/Stop

    nsys start -c cudaProfileApi
    nsys launch -w true <application> [application-arguments]

Effect: Create interactive CLI process and set it up to begin collecting as soon as a cudaProfileStart() is detected. Launch application for default analysis, sending application output to the terminal. Stop collection at next call to cudaProfilerStop, when the user calls `nsys stop`, or when the root process terminates. Generate the report#.qdrep in the default location.

> Note: | If you call `nsys launch` before `nsys start -c cudaProfilerApi` and the code contains a large number of short duration cudaProfilerStart/Stop pairs, Nsight Systems may be unable to process them correctly, causing a fault. This will be corrected in a future version.

> Note: | The Nsight Systems CLI does not support multiple calls to the cudaProfilerStart/Stop API at this time.

Run application, start/stop collection using NVTX

    nsys start -c nvtx
    nsys launch -w true -p MESSAGE@DOMAIN <application> [application-arguments]

Effect: Create interactive CLI process and set it up to begin collecting as soon as an NVTX range with given message in given domain (capture range) is opened. Launch application for default analysis, sending application output to the terminal. Stop collection when all capture ranges are closed, when the user calls `nsys stop`, or when the root process terminates. Generate the report#.qdrep in the default location.

> Note: | The Nsight Systems CLI only triggers the profiling session for the first capture range.

NVTX capture range can be specified:

- Message@Domain: All ranges with given message in given domain are capture ranges. For example:

      nsys launch -w true -p profiler@service ./app

  This would make the profiling start when the first range with message "profiler" is opened in domain "service".

- Message@*: All ranges with given message in all domains are capture ranges. For example:

      nsys launch -w true -p profiler@* ./app

  This would make the profiling start when the first range with message "profiler" is opened in any domain.

- Message: All ranges with given message in default domain are capture ranges. For example:

      nsys launch -w true -p profiler ./app

  This would make the profiling start when the first range with message "profiler" is opened in the default domain.

- By default only messages, provided by NVTX registered strings are considered to avoid additional overhead. To enable non-registered strings check please launch your application with `NSYS_NVTX_PROFILER_REGISTER_ONLY=0` environment:

      nsys launch -w true -p profiler@service -e NSYS_NVTX_PROFILER_REGISTER_ONLY=0 ./app

Run application, start/stop collection multiple times

The interactive CLI supports multiple sequential collections per launch.

    nsys launch <application> [application-arguments]
    nsys start
    nsys stop
    nsys start
    nsys stop
    nsys shutdown --kill sigkill

Effect: Create interactive CLI and launch an application set up for default analysis. Send application output to the terminal. No data is collected until the start command is executed. Collect data from start until stop requested, generate report#.qstrm in the current working directory. Collect data from second start until the secont stop request, generate report#.qdrep (incremented by one) in the current working directory. Shutdown the interactive CLI and send sigkill to the target application's process group.

> Note: | Calling `nsys cancel` after `nsys start` will cancel the collection without generating a report.

### Example Stats Command Sequences

Display default statistics

`nsys stats report1.qdrep`

Effect: Export an SQLite file named report1.sqlite from report1.qdrep (assuming it does not already exist). Print the default reports in column format to the console.

Note: The following two command sequences should present very similar information:

`nsys profile --stats=true <application>`

or

`nsys profile <application>`

`nsys stats report1.qdrep`

Display specific data from a report

`nsys stats --report gputrace report1.qdrep`

Effect: Export an SQLite file named report1.sqlite from report1.qdrep (assuming it does not already exist). Print the report generated by the `gputrace` script to the console in column format.

Generate multiple reports, in multiple formats, output multiple places

`nsys stats --report gputrace --report gpukernsum --report cudaapisum --format csv,column --output .,- report1.qdrep`

Effect: Export an SQLite file named report1.sqlite from report1.qdrep (assuming it does not already exist). Generate three reports. The first, the `gputrace` report, will be output to the file report1_gputrace.csv in CSV format. The other two reports, `gpukernsum` and `cudaapisum`, will be output to the console as columns of data. Although three reports were given, only two formats and outputs are given. To reconcile this, both the list of formats and outputs is expanded to match the list of reports by repeating the last element.

Submit report data to a command

`nsys stats --report cudaapisum --format table \ --output @"grep -E (-|Name|cudaFree)" test.sqlite`

Effect: Open test.sqlite and run the `cudaapisum` script on that file. Generate table data and feed that into the command `grep -E (-|Name|cudaFree)`. The grep command will filter out everything but the header, formatting, and the `cudaFree` data, and display the results to the console.

Note: When the output name starts with @, it is defined as a command. The command is run, and the output of the report is piped to the command's stdin (standard-input). The command's stdout and stderr remain attached to the console, so any output will be displayed directly to the console.

Be aware there are some limitations in how the command string is parsed. No shell expansions (including *, ?, [], and ~) are supported. The command cannot be piped to another command, nor redirected to a file using shell syntax. The command and command arguments are split on whitespace, and no quotes (within the command syntax) are supported. For commands that require complex command line syntax, it is suggested that the command be put into a shell script file, and the script designated as the output command

### 1.7. Example Output from --stats Option

The `nsys stats` command can be used post analysis to generate specific or personalized reports. For a default fixed set of summary statistics to be automatically generated, you can use the --stats option with the `nsys profile` or `nsys start` command to generate a fixed set of useful summary statistics.

If your run traces CUDA, these include CUDA API, Kernel, and Memory Operation statistics:

If your run traces OS runtime events or NVTX push-pop ranges:

If your run traces graphics debug markers these include DX11 debug markers, DX12 debug markers, Vulkan debug markers or KHR debug markers:

Recipes for these statistics as well as documentation on how to create your own metrics will be available in a future version of the tool.

### 1.8. Importing and Viewing Command Line Results Files

The CLI generates a .qdstrm file. The .qdstrm file is an intermediate result file, not intended for multiple imports. It needs to be processed, either by importing it into the GUI or by using the standalone QdstrmImporter to generate an optimized .qdrep file. Use this .qdrep file when re-opening the result on the same machine, opening the result on a different machine, or sharing results with teammates.

This version of Nsight Systems will attempt to automatically convert the .qdstrm file to a .qdrep file with the same name after the run finishes if the required libraries are available. The ability to turn off auto-conversion will be added in a later version.

Import Into the GUI

The CLI and host GUI versions must match to import a .qdstrm file successfully. The host GUI is backward compatible only with .qdrep files.

Copy the .qdstrm file you are interested in viewing to a system where the Nsight Systems host GUI is installed. Launch the Nsight Systems GUI. Select File->Import... and choose the .qdstrm file you wish to open.

The import of really large, multi-gigabyte, .qdstrm files may take up all of the memory on the host computer and lock up the system. This will be fixed in a later version.

Importing Windows ETL files

For Windows targets, ETL files captured with Xperf or the `log.cmd` command supplied with GPUView in the Windows Performance Toolkit can be imported to create reports as if they were captured with Nsight Systems's "WDDM trace" and "Custom ETW trace" features. Simply choose the .etl file from the Import dialog to convert it to a .qdrep file.

Create .qdrep Using QdstrmImporter

The CLI and QdstrmImporter versions must match to convert a .qdstrm file into a .qdrep file. This .qdrep file can then be opened in the same version or more recent versions of the GUI.

To run QdstrmImporter on the host system, find the QdstrmImporter binary in the Host-x86_64 directory in your installation. QdstrmImporter is available for all host platforms. See options below.

To run QdstrmImporter on the target system, copy the Linux Host-x86_64 directory to the target Linux system or install Nsight Systems for Linux host directly on the target. The Windows or MacOS host QdstrmImporter will not work on a Linux Target. See options below.

Short | Long | Parameter | Description
--- | --- | --- | ---
-h | --help |  | Help message providing information about available options and their parameters.
-v | --version |  | Output QdstrmImporter version information
-i | --input-file | filename or path | Import .qdstrm file from this location.
-o | --output-file | filename or path | Provide a different file name or path for the resulting .qdrep file. Default is the same name and path as the .qdstrm file

### 1.9. Using the CLI to Analyze MPI Codes

### 1.9.1. Tracing MPI API calls

The Nsight Systems CLI has built-in API trace support via `--trace=mpi` option only for the OpenMPI and MPICH implementations of MPI. It traces a default list of synchronous MPI APIs. If you require more control over the list of traced APIs or if you are using a different MPI implementation, see github nvtx pmpi wrappers.

You can use this documentation to generate a shared object to wrap a list of synchronous MPI APIs with NVTX using the MPI profiling interface (PMPI). If you set your LD_PRELOAD environment variable to the path of that object, nsys will capture and report the MPI API trace information when `--trace=nvtx` is used. There is no need to use `--trace=MPI`.

NVTX tracing is automatically enabled when MPI trace is turned on.

### 1.9.2. Using the CLI to Profile Applications Launched with mpirun

This version of the Nsight Systems CLI supports concurrent use of the `nsys profile` command. Each instance will create a separate report file.

You cannot use multiple instances of the interactive CLI concurrently, or use the interactive CLI concurrently with `nsys profile` in this version.

Nsight Systems can be used to profile applications launched with mpirun command. Since concurrent use of the CLI is supported only when using the `nsys profile` command, Nsight Systems cannot profile each node from the GUI or from the interactive CLI.

To profile everything, putting the data in one file:

    nsys [nsys options] mpirun [mpi options]

To profile everything putting the data from each rank into a separate file:

    mpirun [mpi options] nsys profile [nsys options]

To profile a single MPI process use a wrapper script. The following script(called "wrap.sh") runs nsys on rank 0 only:

    #!/bin/bash
    if [[ $OMPI_COMM_WORLD_RANK == 0 ]]; then
    ~/nsys/nsys profile ./myapp "$@" --mydummyargument
    else
    ./myapp "$@"
    fi

and then execute `mpirun ./wrap.sh`.

> Note: | Currently you will need a dummy argument to the process, so that Nsight Systems can decide which process to profile. This means that your process must accept dummy arguments to take advantage of this workaround. This script as written is for Open MPI, but should be easily adaptable to other MPI implementations.

## 2. Profiling from the GUI

### 2.1. Profiling Linux Targets from the GUI

### 2.1.1. Connecting to the Target Device

Nsight Systems provides a simple interface to profile on localhost or manage multiple connections to Linux or Windows based devices via SSH. The network connections manager can be launched through the device selection dropdown:

On x86_64:

On Tegra:

The dialog has simple controls that allow adding, removing, and modifying connections:

Security notice: SSH is only used to establish the initial connection to a target device, perform checks, and upload necessary files. The actual profiling commands and data are transferred through a raw, unencrypted socket. Nsight Systems should not be used in a network setup where attacker-in-the-middle attack is possible, or where untrusted parties may have network access to the target device.

While connecting to the target device, you will be prompted to input the user's password. Please note that if you choose to remember the password, it will be stored in plain text in the configuration file on the host. Stored passwords are bound to the public key fingerprint of the remote device.

The No authentication option is useful for devices configured for passwordless login using `root` username. To enable such a configuration, edit the file `/etc/ssh/sshd_config` on the target and specify the following option:

    PermitRootLogin yes

Then set empty password using `passwd` and restart the SSH service with `service ssh restart`.

Open ports: The Nsight Systems daemon requires port 22 and port 45555 to be open for listening. You can confirm that these ports are open with the following command:

    sudo firewall-cmd --list-ports --permanent
    sudo firewall-cmd --reload

To open a port use the following command, skip `--permanent` option to open only for this session:

    sudo firewall-cmd --permanent --add-port 45555/tcp
    sudo firewall-cmd --reload

Likewise, if you are running on a cloud system, you must open port 22 and port 45555 for ingress.

Kernel Version Number - To check for the version number of the kernel support of Nsight Systems on a target device, run the following command on the remote device:

    cat /proc/quadd/version

Minimal supported version is 1.82.

Additionally, presence of Netcat command (`nc`) is required on the target device. For example, on Ubuntu this package can be installed using the following command:

    sudo apt-get install netcat-openbsd

### 2.1.2. System-Wide Profiling Options

### 2.1.2.1. Linux x86_64

System-wide profiling is available on x86 for Linux targets only when run with root privileges.

Ftrace Events Collection

Select Ftrace events

Choose which events you would like to collect.

GPU Context Switch Trace

Tracing of context switching on the GPU is enabled with driver r435.17 or higher.

Here is a screenshot showing three CUDA kernels running simultaneously in three different CUDA contexts on a single GPU.

### 2.1.2.2. Linux for Tegra

Trace all processes – On compatible devices (with kernel module support version 1.107 or higher), this enables trace of all processes and threads in the system. Scheduler events from all tasks will be recorded.

Collect PMU counters – This allows you to choose which PMU (Performance Monitoring Unit) counters Nsight Systems will sample. Enable specific counters when interested in correlating cache misses to functions in your application.

### 2.1.3. Target Sampling Options

Target sampling behavior is somewhat different for Nsight Systems Workstation Edition and Nsight Systems Embedded Platforms Edition.

### Target Sampling Options for Workstation

Three different backtrace collections options are available when sampling CPU instruction pointers. Backtraces can be generated using Intel (c) Last Branch Record (LBR) registers. LBR backtraces generate minimal overhead but the backtraces have limited depth. Backtraces can also be generated using DWARF debug data. DWARF backtraces incur more overhead than LBR backtraces but have much better depth. Finally, backtraces can be generated using frame pointers. Frame pointer backtraces incur medium overhead and have good depth but only resolve frames in the portions of the application and its libraries (including 3rd party libraries) that were compiled with frame pointers enabled. Normally, frame pointers are disabled by default during compilation.

By default, Nsight Systems will use Intel(c) LBRs if available and fall back to using dwarf unwind if they are not. Choose modes... will allow you to override the default.

The Include child processes switch controls whether API tracing is only for the launched process, or for all existing and new child processes of the launched process. If you are running your application through a script, for example a bash script, you need to set this checkbox.

The Include child processes switch does not control sampling in this version of Nsight Systems. The full process tree will be sampled regardless of this setting. This will be fixed in a future version of the product.

Nsight Systems can sample one process tree. Sampling here means interrupting each processor after a certain number of events and collecting an instruction pointer (IP)/backtrace sample if the processor is executing the profilee.

When sampling the CPU on a workstation target, Nsight Systems traces thread context switches and infers thread state as either Running or Blocked. Note that Blocked in the timeline indicates the thread may be Blocked (Interruptible) or Blocked (Uninterruptible). Blocked (Uninterruptible) often occurs when a thread has transitioned into the kernel and cannot be interrupted by a signal. Sampling can be enhanced with OS runtime libraries tracing; see OS Runtime Libraries Trace for more information.

### Target Sampling Options for Embedded Linux

Currently Nsight Systems can only sample one process. Sampling here means that the profilee will be stopped periodically, and backtraces of active threads will be recorded.

Most applications use stripped libraries. In this case, many symbols may stay unresolved. If unstripped libraries exist, paths to them can be specified using the Symbol locations... button. Symbol resolution happens on host, and therefore does not affect performance of profiling on the target.

Additionally, debug versions of ELF files may be picked up from the target system. Refer to Debug Versions of ELF Files for more information.

### 2.1.4. Hotkey Trace Start/Stop

Nsight Systems Workstation Edition can use hotkeys to control profiling. Press the hotkey to start and/or stop a trace session from within the target application’s graphic window. This is useful when tracing games and graphic applications that use fullscreen display. In these scenarios switching to Nsight Systems' UI would unnecessarily introduce the window manager's footprint into the trace. To enable the use of Hotkey check the Hotkey checkbox in the project settings page:

The default hotkey is F12.

### 2.1.5. Launching and Attaching to Processes

Nsight Systems Embedded Platforms Edition can work with Linux-based devices in three modes:

1. Attaching to a process by name

2. Attaching to a process by name, or launching a new process

3. Attaching to a process by its PID

The purpose of the configuration here is to define which process the profiler will attach to for sampling and tracing. Additionally, the profiler can launch a process prior to attaching to it, ensuring that all environment variables are set correctly to successfully collect trace information.

In Attach only mode, the process is selected by its name and command line arguments, as visible using the `ps` tool.

In Attach or launch mode, the process is to first search as if in the Attach only mode, but if it is not found, the process is launched using the same path and command line arguments. If NVTX, CUDA, or other trace settings are selected, the process will be automatically launched with appropriate environment variables.

Note that in some cases, the capabilities of Nsight Systems are not sufficient to correctly launch the application; for example, if certain environment variables have to be corrected. In this case, the application has to be started manually and Nsight Systems should be used in Attach only mode.

The Edit arguments... link will open an editor window, where every command line argument is edited on a separate line. This is convenient when arguments contain spaces or quotes.

To properly populate the Search criteria field based on a currently running process on the target system, use the Select a process button on the right, which has ellipsis as the caption. The list of processes is automatically refreshed upon opening.

Attach by PID mode should be used to connect to a specific process.

To choose one of the currently running processes on the target system, use the Select a process button on the right.

### 2.2. Profiling Windows Targets from the GUI

Profiling on Windows devices is similar to the profiling on Linux devices. Please refer to the Profiling Linux Targets from the GUI section for the detailed documentation and connection information. The major differences on the platforms are listed below:

### Remoting to a Windows Based Machine

To perform remote profiling to a target Windows based machines, install and configure an OpenSSH Server on the target machine.

### Hotkey Trace Start/Stop

Nsight Systems Workstation Edition can use hotkeys to control profiling. Press the hotkey to start and/or stop a trace session from within the target application’s graphic window. This is useful when tracing games and graphic applications that use fullscreen display. In these scenarios switching to Nsight Systems' UI would unnecessarily introduce the window manager's footprint into the trace. To enable the use of Hotkey check the Hotkey checkbox in the project settings page:

The default hotkey is F12.

Changing the Default Hotkey Binding - A different hotkey binding can be configured by setting the HotKeyIntValue configuration field in the config.ini file.

Set the decimal numeric identifier of the hotkey you would like to use for triggering start/stop from the target app graphics window. The default value is 123 which corresponds to 0x7B, or the F12 key.

Virtual key identifiers are detailed in MSDN's Virtual-Key Codes.

Note that you must convert the hexadecimal values detailed in this page to their decimal counterpart before using them in the file. For example, to use the F1 key as a start/stop trace hotkey, use the following settings in the config.ini file:

    HotKeyIntValue=112

### Target Sampling Options on Windows

Nsight Systems can sample one process tree. Sampling here means interrupting each processor periodically. The sampling rate is defined in the project settings and is either 100Hz, 1KHz (default value), 2Khz, 4KHz, or 8KHz.

On Windows, Nsight Systems can collect thread activity of one process tree. Collecting thread activity means that each thread context switch event is logged and (optionally) a backtrace is collected at the point that the thread is scheduled back for execution. Thread states are displayed on the timeline.

If it was collected, the thread backtrace is displayed when hovering over a region where the thread execution is blocked.

### Symbol Locations

Symbol resolution happens on host, and therefore does not affect performance of profiling on the target.

Press the Symbol locations... button to open the Configure debug symbols location dialog.

Use this dialog to specify:

- Paths of PDB files

- Symbols servers

- The location of the local symbol cache

To use a symbol server:

1. Install Debugging Tools for Windows, a part of the Windows 10 SDK.

2. Add the symbol server URL using the Add Server button.

   Information about Microsoft's public symbol server, which enables getting Windows operating system related debug symbols can be found here.

### 2.3. Profiling Android Targets from the GUI

Profiling on Android devices is similar to the profiling on Linux devices. Please refer to the Profiling Linux Targets from the GUI section for the detailed documentation. The major differences on the platforms are listed below:

### Configuring Your Android Device

To work with Nsight Systems, the target Android device should be configured for USB debugging in the Developer options settings menu. Please refer to Android development documentation to learn how to configure the device for USB debugging.

On the host, a compatible USB driver should be installed. Please refer to device manufacturer's documentation to learn how to obtain and install the driver.

Connect your target device via a USB cable and power it on (or wake it up). Make sure that you have the `adb` command available (it is part of Android SDK Platform Tools package). Nsight Systems can only connect to devices that are marked as `device` in the output of the `adb devices` command. Make sure you can enter the ADB shell of the target device by running `adb shell` on the host.

Launch the Nsight Systems application. On the first launch, a new project called `Project 1` is created automatically.

When connecting to the target device, Nsight Systems will validate it and install its daemon into the following location on the device:

    /data/local/tmp/com.nvidia.nsightsystems.tools/

Once the daemon and all required files are installed correctly, a green check mark will appear and `Device is ready` text will be displayed:

### Application

This section allows you to choose which application to profile. All information will be collected about the main process of the selected application, except when the Trace all processes checkbox is enabled.

For non-rooted Android devices, the list of applications only shows information about debuggable applications. By default, applications that are being developed using the Android SDK already contain the debuggable option in their manifests.

On rooted Android devices, profiling of all applications is allowed.

For convenience, the application list also shows the process identifiers (PID) of processes correlated to the listed packages. To refresh this information, use the button in the upper right corner of the list.

The two checkboxes below the application list are important to ensure that the correct launch or attach behavior is configured.

Allow sending intent to launch the default activity, when unselected, forces the profiler to attach to a running process. If no processes are found to correlate to the specified application name, the profiling session fails to start with an error message. When selected, Nsight Systems may launch the default intent of the selected application to make sure it is running and appears on top of the screen on the target device.

In some applications, especially in early stages of development, common bugs related to handling the lifecycle of activities can be found. In such cases, sending the default intent may lead to undesired behavior or even crashes of the profilee. Leaving the checkbox unselected ensures that the profiler does not affect the application.

Restart application if running is a convenient option in two cases:

1. When profiling from the very beginning of the application is desired.

2. When using some of the trace features described below. They require that a special library is injected into the application in runtime, which happens when the application is paused by the Android runtime's virtual machine just after starting. In this case, enabling this option helps ensure that the application is always restarted and the injection always happens, as opposed to potentially attaching to the application's process without injection.

   Collect NVTX trace. See NVTX Trace for more information.

   Collect OpenGL trace. See OpenGL Trace for more information.

### 2.4. Profiling QNX Targets from the GUI

Profiling on QNX devices is similar to the profiling on Linux devices. Please refer to the Profiling Linux Targets from the GUI section for the detailed documentation. The major differences on the platforms are listed below:

- Backtrace sampling is not supported. Instead backtraces are collected for long OS runtime libraries calls. Please refer to the OS Runtime Libraries Trace section for the detailed documentation.

- CUDA support is limited to CUDA 9.0+

- Filesystem on QNX device might be mounted read-only. In that case Nsight Systems is not able to install target-side binaries, required to run the profiling session. Please make sure that target filesystem is writable before connecting to QNX target. For example, make sure the following command works:

      echo XX > /xx && ls -l /xx

## 3. Export Formats

### SQLite Schema Reference

Nsight Systems has the ability to export SQLite database files from the.qdrep results file. From the CLI, use `nsys export`. From the GUI, call `File->Export...`. Complete documentation of the schema, with samples is installed with the product in the documentation\nsys-exporter directory.

Note: The .qdrep report format is the the only data format for Nsight Systems that should be considered forward compatible. The SQLite schema can and will change in the future.

The schema for a concrete database can be obtained with the sqlite3 tool built-in command `.schema`. The sqlite3 tool can be located in the Target directory of your Nsight Systems installation.

    sqlite> .schema
    CREATE TABLE StringIds (id INTEGER PRIMARY KEY, value TEXT NOT NULL);
    CREATE TABLE SCHED_EVENTS (id INTEGER PRIMARY KEY AUTOINCREMENT, start INT NOT NULL, cpu INT NOT NULL, isSchedIn INT NOT NULL, globalTid INT NOT NULL);
    CREATE TABLE sqlite_sequence(name,seq);
    CREATE TABLE COMPOSITE_EVENTS (id INT NOT NULL PRIMARY KEY, start INT NOT NULL, cpu INT NOT NULL, threadState INT NOT NULL, globalTid INT NOT NULL, cpuCycles INT NOT NULL);
    ...

Note: Currently tables are created lazily therefore not every table described in the documentation will be present in a particular database. This will change in a future version of the product

Currently, a table is created for each data type in the exported database. Since usage patterns for exported data may vary greatly and no default use cases have been established, no indexes or extra constraints are created. Instead, refer to the Examples section in your installed documentation directory for a list of common recipes. This may change in a future version of the product.

Due to current limitations, all fields are declared as NOT NULL, even if the actual value may be missing. If the value is missing, the cell is set to the default value for that field. This might change in future versions.

### JSON and Text Format Description

JSON and TXT export formats are generated by serializing buffered messages, each on a new line. First, all collected events are processed. Then strings are serialized, followed by stdout, stderr streams if any, followed by thread names.

Output layout:

    {Event #1}
    {Event #2}
    ...
    {Event #N}
    {Strings}
    {Streams}
    {Threads}

For easier grepping of JSON output, the `--separate-strings` switch may be used to force manual splitting of strings, streams and thread names data.

Example line split: `nsys export --export-json --separate-strings sample.qdrep -- -`

    {"type":"String","id":"3720","value":"Process 14944 was launched by the profiler"}
    {"type":"String","id":"3721","value":"Profiling has started."}
    {"type":"String","id":"3722","value":"Profiler attached to the process."}
    {"type":"String","id":"3723","value":"Profiling has stopped."}
    {"type":"ThreadName","globalTid":"72057844756653436","nameId":"14","priority":"10"}
    {"type":"ThreadName","globalTid":"72057844756657940","nameId":"15","priority":"10"}
    {"type":"ThreadName","globalTid":"72057844756654400","nameId":"24","priority":"10"}

Compare with: `nsys export --export-json sample.qdrep -- -`

    {"data":["[Unknown]","[Unknown kernel module]","[Max depth]","[Broken backtraces]",
      "[Called from Java]","QnxKernelTrace","mm_","task_submit","class_id","syncpt_id",
      "syncpt_thresh","pid","tid","FTrace","[NSys]","[NSys Comms]", "..." ,"Process
      14944 was launched by the profiler","Profiling has started.","Profiler attached
      to the process.","Profiling has stopped."]}
    {"data":[{"nameIdx":"14","priority":"10","globalTid":"72057844756653436"},
      {"nameIdx":"15","priority":"10","globalTid":"72057844756657940"},{"nameIdx":"24",
      "priority":"10","globalTid":"72057844756654400"}]}

Note, that only last few lines are shown here for clarity and that carriage returns and indents were added to avoid wrapping documentation.

## 4. Report Scripts

### Report Scripts Shipped With Nsight Systems

The Nsight Systems development team created and maintains a set of report scripts for some of the commonly requested reports. These scripts will be updated to adapt to any changes in SQLite schema or internal data structures.

These scripts are located in the Nsight Systems package in the Target-<architecture>/reports directory. The following standard reports are available:

### apigpusum[:base] -- CUDA API & GPU Summary (CUDA API + kernels + memory ops)

Arguments

- base - Optional argument, if given, will cause summary to be over the base name of the kernel, rather than the templated name.

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this kernel
- Instances: The number of executions of this object
- Average : The average execution time of this kernel
- Minimum : The smallest execution time of this kernel
- Maximum : The largest execution time of this kernel
- Category : The category of the operation
- Operation : The name of the kernel

This report provides a summary of CUDA API calls, kernels and memory operations, and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that API call's, kernel's, or memory operation's percent of the execution time of the APIs, kernels and memory operations listed, and not a percentage of the application wall or CPU execution time.

This report combines data from the `cudaapisum`, `gpukernsum`, and `gpumemsizesum` reports. It is very similar to profile section of `nvprof --dependency-analysis`.

### cudaapisum -- CUDA API Summary

Arguments - None

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this function
- Num Calls : The number of calls to this function
- Average : The average execution time of this function
- Minimum : The smallest execution time of this function
- Maximum : The largest execution time of this function
- Name : The name of the function

This report provides a summary of CUDA API functions and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that function's percent of the execution time of the functions listed, and not a percentage of the application wall or CPU execution time.

### cudaapitrace -- CUDA API Trace

Arguments - None

Output: All time values given in nanoseconds

- Start : Timestamp when API call was made
- Duration : Length of API calls
- Name : API function name
- Result : return value of API call
- CorrID : Correlation used to map to other CUDA calls
- Pid : Process ID that made the call
- Tid : Thread ID that made the call
- T-Pri : Run priority of call thread
- Thread Name : Name of thread that called API function

This report provides a trace record of CUDA API function calls and their execution times.

### gpukernsum[:base] -- CUDA GPU Kernel Summary

Arguments

- base - Optional argument, if given, will cause summary to be over the base name of the kernel, rather than the templated name.

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this kernel
- Instances : The number of calls to this kernal
- Average : The average execution time of this kernal
- Minimum : The smallest execution time of this kernal
- Maximum : The largest execution time of this kernal
- Name : The name of the kernal

This report provides a summary of CUDA kernels and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that kernel's percent of the execution time of the kernels listed, and not a percentage of the application wall or CPU execution time.

### gpumemsizesum -- GPU Memory Operations Summary (by Size)

Arguments - None

Output: All memory values given in KiB

- Total : Total number of KiB utilized by this operation
- Operations : Number of executions of this operation
- Average : The average memory size of this operation
- Minimum : The smallest memory size of this operation
- Maximum : The largest memory size of this operation
- Name : The name of the operation

This report provides a summary of GPU memory operations and the amount of memory they utilize.

### gpumemtimesum -- GPU Memory Operations Summary (by Time)

Arguments - None

Output: All memory values given in KiB

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this operation
- Operations: The number of operations of this type
- Average : The average execution time of this operation
- Minimum : The smallest execution time of this operation
- Maximum : The largest execution time of this operation
- Operation : The name of the memory operation

This report provides a summary of GPU memory operations and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that operation's percent of the execution time of the operations listed, and not a percentage of the application wall or CPU execution time.

### gpusum[:base] -- GPU Summary (kernels + memory operations)

Arguments

- base - Optional argument, if given, will cause summary to be over the base name of the kernel, rather than the templated name.

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this kernel
- Instances : The number of executions of this object
- Average : The average execution time of this kernal
- Minimum : The smallest execution time of this kernal
- Maximum : The largest execution time of this kernal
- Category : The category of the operation
- Name : The name of the kernal

This report provides a summary of CUDA kernels and memory operations, and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that kernel's or memory operation's percent of the execution time of the kernels and memory operations listed, and not a\ percentage of the application wall or CPU execution time.

This report combines data from the `gpukernsum` and `gpumemtimesum` reports. This report is very similar to output of the command `nvprof --print-gpu-summary`.

### gputrace -- CUDA GPU Trace

Arguments - None

Output:

- Start : Start time of trace event in seconds
- Duration : Length of event in nanoseconds
- CorrId : Correlation ID
- GrdX, GrdY, GrdZ : Grid values
- BlkX, BlkY, BlkZ : Block values
- Reg/Trd : Registers per thread
- StcSMem : Size of Static Shared Memory
- DymSMem : Size of Dynamic Shared Memory
- Bytes : Size of memory operation
- Thru : Throughput in MB per Second
- SrcMemKd : Memcpy source memory kind or memset memory kind
- DstMemKd : Memcpy destination memory kind
- Device : GPU device name and ID
- Ctx : Context ID
- Strm : Stream ID
- Name : Trace event name

This report displays a trace of CUDA kernels and memory operations. Items are sorted by start time.

### nvtxppsum -- NVTX Push/Pop Range Summary

Arguments - None

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all instances of this range
- Instances : The number of instances of this range
- Average : The average execution time of this range
- Minimum : The smallest execution time of this range
- Maximum : The largest execution time of this range
- Range : The name of the range

This report provides a summary of NV Tools Extensions Push/Pop Ranges and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that range's percent of the execution time of the ranges listed, and not a percentage of the application wall or CPU execution time.

### openmpevtsum -- OpenMP Event Summary

Arguments - None

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of event type
- Count : The number of event type
- Average : The average execution time of event type
- Minimum : The smallest execution time of event type
- Maximum : The largest execution time of event type
- Name : The name of the event

This report provides a summary of OpenMP events and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that event type's percent of the execution time of the events listed, and not a percentage of the application wall or CPU execution time.

### osrtsum -- OS Runtime Summary

Arguments - None

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this function
- Num Calls : The number of calls to this function
- Average : The average execution time of this function
- Minimum : The smallest execution time of this function
- Maximum : The largest execution time of this function
- Name : The name of the function

This report provides a summary of operating system functions and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that function's percent of the execution time of the functions listed, and not a percentage of the application wall or CPU execution time.

### vulkanmarkerssum -- Vulkan Range Summary

Arguments - None

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this function
- Instances : The number of instances of this range
- Average : The average execution time of this function
- Minimum : The smallest execution time of this function
- Maximum : The largest execution time of this function
- StdDev : The standard deviation of execution time of this range
- Range : The name of the range

This report provides a summary of Vulkan debug markers on the CPU, and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that function's percent of the execution time of the functions listed, and not a percentage of the application wall or CPU execution time.

### pixsum -- PIX Range Summary

Arguments - None

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this function
- Instances : The number of instances of this range
- Average : The average execution time of this function
- Minimum : The smallest execution time of this function
- Maximum : The largest execution time of this function
- StdDev : The standard deviation of execution time of this range
- Range : The name of the range

This report provides a summary of PIX CPU debug markers, and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that function's percent of the execution time of the functions listed, and not a percentage of the application wall or CPU execution time.

### pixsum -- OpenGL KHR_debug Range Summary

Arguments - None

Output: All time values given in nanoseconds

- Time(%) : Percentage of Total Time
- Total Time : The total time used by all executions of this function
- Instances : The number of instances of this range
- Average : The average execution time of this function
- Minimum : The smallest execution time of this function
- Maximum : The largest execution time of this function
- StdDev : The standard deviation of execution time of this range
- Range : The name of the range

This report provides a summary of OpenGL KHR_debug CPU PUSH/POP debug Ranges, and their execution times. Note that the Time(%) column is calculated using a summation of the Total Time column, and represents that function's percent of the execution time of the functions listed, and not a percentage of the application wall or CPU execution time.

### Report Formatters Shipped With Nsight Systems

The following formats are available in Nsight Systems

### Column

Usage:

`column[:nohdr][:nolimit][:nofmt][:<width>[:<width>]...]`

Arguments

- nohdr : Do not display the header
- nolimit : Remove 100 character limit from auto-width columns Note: This can result in extremely wide columns.
- nofmt : Do not reformat numbers.
- <width>... : Define the explicit width of one or more columns. If the value "." is given, the column will auto-adjust. If a width of 0 is given, the column will not be displayed.

The column formatter presents data in vertical text columns. It is primarily designed to be a human-readable format for displaying data on a console display.

Text data will be left-justified, while numeric data will be right-justified. If the data overflows the available column width, it will be marked with a "…" character, to indicate the data values were clipped. Clipping always occurs on the right-hand side, even for numeric data.

Numbers will be reformatted to make easier to visually scan and understand. This includes adding thousands-separators. This process requires that the string representation of the number is converted into its native representation (integer or floating point) and then converted back into a string representation to print. This conversion process attempts to preserve elements of number presentation, such as the number of decimal places, or the use of scientific notation, but the conversion is not always perfect (the number should always be the same, but the presentation may not be). To disable the reformatting process, use the argument `nofmt`.

If no explicit width is given, the columns auto-adjust their width based off the header size and the first 100 lines of data. This auto-adjustment is limited to a maximum width of 100 characters. To allow larger auto-width columns, pass the initial argument `nolimit`. If the first 100 lines do not calculate the correct column width, it is suggested that explicit column widths be provided.

### Table

Usage:

`table[:nohdr][:nolimit][:nofmt][:<width>[:<width>]...]`

Arguments

- nohdr : Do not display the header
- nolimit : Remove 100 character limit from auto-width columns Note: This can result in extremely wide columns.
- nofmt : Do not reformat numbers.
- <width>... : Define the explicit width of one or more columns. If the value "." is given, the column will auto-adjust. If a width of 0 is given, the column will not be displayed.

The table formatter presents data in vertical text columns inside text boxes. Other than the lines between columns, it is identical to the column formatter.

### CSV

Usage:

`csv[:nohdr]`

Arguments

- nohdr : Do not display the header

The csv formatter outputs data as comma-separated values. This format is commonly used for import into other data applications, such as spread-sheets and databases.

There are many different standards for CSV files. Most differences are in how escapes are handled, meaning data values that contain a comma or space.

This CSV formatter will escape commas by surrounding the whole value in double-quotes.

### TSV

Usage:

`tsv[:nohdr][:esc]`

Arguments

- nohdr : Do not display the header
- esc : escape tab characters, rather than removing them

The tsv formatter outputs data as tab-separated values. This format is sometimes used for import into other data applications, such as spreadsheets and databases.

Most TSV import/export systems disallow the tab character in data values. The formatter will normally replace any tab characters with a single space. If the `esc` argument has been provided, any tab characters will be replaced with the literal characters "\t".

### JSON

Usage:

`json`

Arguments: no arguments

The json formatter outputs data as an array of JSON objects. Each object represents one line of data, and uses the column names as field labels. All objects have the same fields. The formatter attempts to recognize numeric values, as well as JSON keywords, and converts them. Empty values are passed as an empty string (and not nil, or as a missing field).

At this time the formatter does not escape quotes, so if a data value includes double-quotation marks, it will corrupt the JSON file.

### HDoc

Usage:

`hdoc[:title=<title>][:css=<URL>]`

Arguments:

- title : string for HTML document title
- css : URL of CSS document to include

The hdoc formatter generates a complete, verifiable (mostly), standalone HTML document. It is designed to be opened in a web browser, or included in a larger document via an <iframe>.

### HTable

Usage:

`htable`

Arguments: no arguments

The htable formatter outputs a raw HTML <table> without any of the surrounding HTML document. It is designed to be included into a larger HTML document. Although most web browsers will open and display the document, it is better to use the hdoc format for this type of use.

## 5. Migrating from NVIDIA nvprof

### Using the Nsight Systems CLI nvprof Command

The `nvprof` command of the Nsight Systems CLI is intended to help former nvprof users transition to nsys. Many nvprof switches are not supported by nsys, often because they are now part of NVIDIA Nsight Compute.

The full nvprof documentation can be found at https://docs.nvidia.com/cuda/profiler-users-guide.

The nvprof transition guide for Nsight Compute can be found at https://docs.nvidia.com/nsight-compute/NsightComputeCli/index.html#nvprof-guide.

Any nvprof switch not listed below is not supported by the `nsys nvprof` command. No additional nsys functionality is available through this command. New features will not be added to this command in the future.

### CLI nvprof Command Switch Options

After choosing the `nvprof` command switch, the following options are available. When you are ready to move to using Nsight Systems CLI directly, see Command Line Options documentation for the nsys switch(es) given below. Note that the nsys implementation and output may vary from nvprof.

Usage.

    nsys nvprof [options]

Switch | Parameters (Default in Bold) | nsys switch | Switch Description
--- | --- | --- | ---
--annotate-mpi | off, openmpi, mpich | --trace=mpi AND --mpi-impl | Automatically annotate MPI calls with NVTX markers. Specify the MPI implementation installed on your machine. Only OpenMPI and MPICH implementations are supported.
--cpu-thread-tracing | on, off | --trace=osrt | Collect information about CPU thread API activity.
--profile-api-trace | none, runtime, driver,all | --trace=cuda | Turn on/off CUDA runtime and driver API tracing. For Nsight Systems there is no separate CUDA runtime and CUDA driver trace, so selecting `runtime` or `driver` is equivalent to selecting `all` .
--profile-from-start | on, off | if off use --capture-range=cudaProfilerApi | Enable/disable profiling from the start of the application. If disabled, the application can use {cu,cuda}Profiler{Start,Stop} to turn on/off profiling.
-t,--timeout | <nanoseconds> default=0 | --duration=seconds | If greater than 0, stop the collection and kill the launched application after timeout seconds. nvprof started counting when the CUDA driver is initialized. nsys starts counting immediately.
--cpu-profiling | on, off | --sampling=cpu | Turn on/off CPU profiling
--openacc-profiling | on, off | --trace=openacc to turn on | Enable/disable recording information from the OpenACC profiling interface. Note: OpenACC profiling interface depends on the presence of the OpenACC runtime. For supported runtimes, see CUDA Trace section of documentation

-o, --export-profile

<filename>

--output={filename} and/or --export=sqlite

Export named file to be imported or opened in the Nsight Systems GUI. %q{ENV_VAR} in string will be replaced with the set value of the environment variable. If not set this is an error. %h in the string is replaced with the system hostname. %% in the string is replaced with %. %p in the string is not supported currently. Any other character following % is illegal. The default is report1, with the number incrementing to avoid overwriting files, in users working directory.

-f, --force-overwrite |  | --force-overwrite=true | Force overwriting all output files with same name.
-h, --help |  | --help | Print Nsight Systems CLI help
-V, --version |  | --version | Print Nsight Systems CLI version information

### Next Steps

NVIDIA Visual Profiler (NVVP) and NVIDIA nvprof are deprecated. New GPUs and features will not be supported by those tools. We encourage you to make the move to Nsight Systems now. For additional information, suggestions, and rationale, see the blog series in Other Resources.

## 6. Profiling in a Docker on Linux Devices

Collecting data within a Docker

The following information assumes the reader is knowledgeable regarding Docker containers. For further information about Docker use in general, see the Docker documentation.

Enable Docker Collection

When starting the Docker to perform a Nsight Systems collection, additional steps are required to enable the `perf_event_open` system call. This is required in order to utilize the Linux kernel’s perf subsystem which provides sampling information to Nsight Systems.

There are three ways to enable the `perf_event_open` syscall. You can enable it by using the `--privileged=true` switch, adding `--cap-add=SYS_ADMIN` switch to your docker run command file, or you can enable it by setting the seccomp security profile if your system meets the requirements.

Secure computing mode (seccomp) is a feature of the Linux kernel that can be used to restrict an application's access. This feature is available only if the kernel is enabled with seccomp support. To check for seccomp support:

    $ grep CONFIG_SECCOMP= /boot/config-$(uname -r)

The official Docker documentation says:

    "Seccomp profiles require seccomp 2.2.1 which is not available on Ubuntu 14.04, Debian Wheezy, or Debian Jessie. To use seccomp on these distributions, you must download the latest static Linux binaries (rather than packages)."

Download the default seccomp profile file, default.json, relevant to your Docker version. If `perf_event_open` is already listed in the file as guarded by `CAP_SYS_ADMIN`, then remove the `perf_event_open` line. Add the following lines under "syscalls" and save the resulting file as `default_with_perf.json`.

    {
        "name": "perf_event_open",
        "action": "SCMP_ACT_ALLOW",
        "args": []
    },

Then you will be able to use the following switch when starting the Docker to apply the new seccomp profile.

    --security-opt seccomp=default_with_perf.json

Launch Docker Collection

Here is an example command that has been used to launch a Docker for testing with Nsight Systems:

    sudo nvidia-docker run --network=host --security-opt
    seccomp=default_with_perf.json --rm -ti caffe-demo2 bash

There is a known issue where Docker collections terminate prematurely with older versions of the driver and the CUDA Toolkit. If collection is ending unexpectedly, please update to the latest versions.

After the Docker has been started, use the Nsight Systems CLI to launch a collection within the Docker. The resulting .qdstrm file can be imported into the Nsight Systems host like any other CLI result.

## 7. Direct3D Trace

Nsight Systems has the ability to trace both the Direct3D 11 API and the Direct3D 12 API on Windows targets.

### 7.1. D3D11 API trace

Nsight Systems can capture information about Direct3D 11 API calls made by the profiled process. This includes capturing the execution time of D3D11 API functions, performance markers, and frame durations.

SLI Trace

Trace SLI queries and peer-to-peer transfers of D3D11 applications. Requires SLI hardware and an active SLI profile definition in the NVIDIA console.

### 7.2. D3D12 API Trace

Direct3D 12 is a low-overhead 3D graphics and compute API for Microsoft Windows. Information about Direct3D 12 can be found at the Direct3D 12 Programming Guide.

Nsight Systems can capture information about Direct3D 12 usage by the profiled process. This includes capturing the execution time of D3D12 API functions, corresponding workloads executed on the GPU, performance markers, and frame durations.

The Command List Creation row displays time periods when command lists were being created. This enables developers to improve their application’s multithreaded command list creation. Command list creation time period is measured between the call to `ID3D12GraphicsCommandList::Reset` and the call to `ID3D12GraphicsCommandList::Close`.

The GPU row shows an aggregated view of D3D12 API calls and GPU workloads. Note that not all D3D12 API calls are logged.

A Command Queue row is displayed for each D3D12 command queue created by the profiled application. The row’s header displays the queue's running index and its type (Direct, Compute, Copy).

The API row displays time periods where `ID3D12CommandQueue::ExecuteCommandLists` was called. The GPU Workload row displays time periods where workloads were executed by the GPU. The workload’s type (Graphics, Compute, Copy, etc.) is displayed on the bar representing the workload’s GPU execution.

In addition, you can see the PIX command queue CPU-side performance markers, GPU-side performance markers and the GPU Command List performance markers, each in their row.

Clicking on a GPU workload highlights the corresponding `ID3D12CommandQueue::ExecuteCommandLists`, `ID3D12GraphicsCommandList::Reset` and `ID3D12GraphicsCommandList::Close API` calls, and vice versa.

Detecting which CPU thread was blocked by a fence can be difficult in complex apps that run tens of CPU threads. The timeline view displays the 3 operations involved:

- The CPU thread pushing a signal command and fence value into the command queue. This is displayed on the DX12 Synchronization sub-row of the calling thread.

- The GPU executing that command, setting the fence value and signaling the fence. This is displayed on the GPU Queue Synchronization sub-row.

- The CPU thread calling a Win32 wait API to block-wait until the fence is signaled. This is displayed on the Thread's OS runtime libraries row.

Clicking one of these will highlight it and the corresponding other two calls.

## 8. WDDM Queues

The Windows Display Driver Model (WDDM) architecture uses queues to send work packets from the CPU to the GPU. Each D3D device in each process is associated with one or more contexts. Graphics, compute, and copy commands that the profiled application uses are associated with a context, batched in a command buffer, and pushed into the relevant queue associated with that context.

Nsight Systems can capture the state of these queues during the trace session.

Enabling the "Collect additional range of ETW events" option will also capture extended DxgKrnl events such as context status, allocations, sync wait, signal events, etc.

A command buffer in a WDDM queues may have one the following types:

- Render

- Deferred

- System

- MMIOFlip

- Wait

- Signal

- Device

- Software

It may also be marked as a Present buffer, indicating that the application has finished rendering and requests to display the source surface.

See the Microsoft documentation for the WDDM architecture and the DXGKETW_QUEUE_PACKET_TYPE enumeration.

To retain the .etl trace files captured, so that they can be viewed in other tools (e.g. GPUView), change the "Save ETW log files in project folder" option under "Profile Behavior" in Nsight Systems's global Options dialog. The .etl files will appear in the same folder as the .qdrep file, accessible by right-clicking the report in the Project Explorer and choosing "Show in Folder...". Data collected from each ETW provider will appear in its own .etl file, and an additional .etl file named "Report XX-Merged-*.etl", containing the events from all captured sources, will be created as well.

## 9. Vulkan API Trace

### 9.1. Vulkan Overview

Vulkan is a low-overhead, cross-platform 3D graphics and compute API, targeting a wide variety of devices from PCs to mobile phones and embedded platforms. The Vulkan API is defined by the Khronos Group. Information about Vulkan and the Khronos Group can be found at the Khronos Vulkan Site.

Nsight Systems can capture information about Vulkan usage by the profiled process. This includes capturing the execution time of Vulkan API functions, corresponding GPU workloads, debug util labels, and frame durations. Vulkan profiling is supported on both Windows and x86 Linux operating systems.

The Command Buffer Creation row displays time periods when command buffers were being created. This enables developers to improve their application’s multi-threaded command buffer creation. Command buffer creation time period is measured between the call to `vkBeginCommandBuffer` and the call to `vkEndCommandBuffer`.

The Swap chains row displays the available swap chains and the time periods where `vkQueuePresentKHR` was executed on each swap chain.

A Queue row is displayed for each Vulkan queue created by the profiled application. The API sub-row displays time periods where `vkQueueSubmit` was called. The GPU Workload sub-row displays time periods where workloads were executed by the GPU.

In addition, you can see Vulkan debug util labels on both the CPU and the GPU.

Clicking on a GPU workload highlights the corresponding `vkQueueSubmit` call, and vice versa.

### 9.2. Pipeline Creation Feedback

When tracing target application calls to Vulkan pipeline creation APIs, Nsight Systems leverages the Pipeline Creation Feedback extension to collect more details about the duration of individual pipeline creation stages.

See Pipeline Creation Feedback extension for details about this extension.

Vulkan pipeline creation feedback is available on NVIDIA driver release 435 or later.

### 9.3. Vulkan GPU Trace Notes

- Vulkan GPU trace is available only when tracing apps that use NVIDIA GPUs.

- The endings of Vulkan Command Buffers execution ranges on Compute and Transfer queues may appear earlier on the timeline than their actual occurrence.

## 10. Stutter Analysis

## Stutter Analysis Overview

Nsight Systems on Windows targets displays stutter analysis visualization aids for profiled graphics applications that use either OpenGL, D3D11, D3D12 or Vulkan, as detailed below in the following sections.

### 10.1. FPS Overview

The Frame Duration section displays frame durations on both the CPU and the GPU.

The frame duration row displays live FPS statistics for the current timeline viewport. Values shown are:

1. Number of CPU frames shown of the total number captured

2. Average, minimal, and maximal CPU frame time of the currently displayed time range

3. Average FPS value for the currently displayed frames

4. The 99th percentile value of the frame lengths (such that only 1% of the frames in the range are longer than this value).

The values will update automatically when scrolling, zooming or filtering the timeline view.

The stutter row highlights frames that are significantly longer than the other frames in their immediate vicinity.

The stutter row uses an algorithm that compares the duration of each frame to the median duration of the surrounding 19 frames. Duration difference under 4 milliseconds is never considered a stutter, to avoid cluttering the display with frames whose absolute stutter is small and not noticeable to the user.

For example, if the stutter threshold is set at 20%:

1. Median duration is 10 ms. Frame with 13 ms time will not be reported (relative difference > 20%, absolute difference < 4 ms)

2. Median duration is 60 ms. Frame with 71 ms time will not be reported (relative difference < 20%, absolute difference > 4 ms)

3. Median duration is 60 ms. Frame with 80 ms is a stutter (relative difference > 20%, absolute difference > 4 ms, both conditions met)

OSC detection

The "19 frame window median" algorithm by itself may not work well with some cases of "oscillation" (consecutive fast and slow frames), resulting in some false positives. The median duration is not meaningful in cases of oscillation and can be misleading.

To address the issue and identify if oscillating frames, the following method is applied:

1. For every frame, calculate the median duration, 1st and 3rd quartiles of 19-frames window.

2. Calculate the delta and ratio between 1st and 3rd quartiles.

3. If the 90th percentile of 3rd – 1st quartile delta array > 4 ms AND the 90th percentile of 3rd/1st quartile array > 1.2 (120%) then mark the results with "OSC" text.

Right-clicking the Frame Duration row caption lets you choose the target frame rate (30, 60, 90 or custom frames per second).

By clicking the Customize FPS Display option, a customization dialog pops up. In the dialog, you can now define the frame duration threshold to customize the view of the potentially problematic frames. In addition, you can define the threshold for the stutter analysis frames.

Frame duration bars are color coded:

- Green, the frame duration is shorter than required by the target FPS ratio.

- Yellow, duration is slightly longer than required by the target FPS rate.

- Red, duration far exceeds that required to maintain the target FPS rate.

The CPU Frame Duration row displays the CPU frame duration measured between the ends of consecutive frame boundary calls:

- The OpenGL frame boundaries are `eglSwapBuffers/glXSwapBuffers/SwapBuffers` calls.

- The D3D11 and D3D12 frame boundaries are `IDXGISwapChainX::Present` calls.

- The Vulkan frame boundaries are `vkQueuePresentKHR` calls.

The GPU Frame Duration row displays the time measured between

- The start time of the first GPU workload execution of this frame.

- The start time of the first GPU workload execution of the next frame.

Reflex SDK

NVIDIA Reflex SDK is a series of NVAPI calls that allow applications to integrate the Ultra Low Latency driver feature more directly into their game to further optimize synchronization between simulation and rendering stages and lower the latency between user input and final image rendering. For more details about Reflex SDK, see Reflex SDK Site.

Nsight Systems will automatically capture NVAPI functions when either Direct3D 11, Direct3D 12, or Vulkan API trace are enabled.

The Reflex SDK row displays timeline ranges for the following types of latency markers:

- RenderSubmit.

- Simulation.

- Present.

- Driver.

- OS Render Queue.

- GPU Render.

### 10.2. Frame Health

The Frame Health row displays actions that took significantly a longer time during the current frame, compared to the median time of the same actions executed during the surrounding 19-frames. This is a great tool for detecting the reason for frame time stuttering. Such actions may be: shader compilation, present, memory mapping, and more. Nsight Systems measures the accumulated time of such actions in each frame. For example: calculating the accumulated time of shader compilations in each frame and comparing it to the accumulated time of shader compilations in the surrounding 19 frames.

Example of a Vulkan frame health row:

### 10.3. GPU Memory Utilization

The Memory Utilization row displays the amount of used local GPU memory and the commit limit for each GPU.

Note that this is not the same as the CUDA kernel memory allocation graph, see CUDA GPU Memory Graph for that functionality.

### 10.4. Vertical Synchronization

The VSYNC rows display when the monitor's vertical synchronizations occur.

## 11. OpenMP Trace

Nsight Systems for Linux x86_64 and Power targets is capable of capturing information about OpenMP events. This functionality is built on the OpenMP Tools Interface (OMPT), full support is available only for runtime libraries supporting tools interface defined in OpenMP 5.0 or greater.

As an example, LLVM OpenMP runtime library partially implements tools interface. If you use PGI compiler <= 20.4 to build your OpenMP applications, add -mp=libomp switch to use LLVM OpenMP runtime and enable OMPT based tracing. If you use Clang, make sure the LLVM OpenMP runtime library you link to was compiled with tools interface enabled.

Only a subset of the OMPT callbacks are processed:

    ompt_callback_parallel_begin
    ompt_callback_parallel_end
    ompt_callback_sync_region
    ompt_callback_task_create
    ompt_callback_task_schedule
    ompt_callback_implicit_task
    ompt_callback_master
    ompt_callback_reduction
    ompt_callback_task_create
    ompt_callback_cancel
    ompt_callback_mutex_acquire, ompt_callback_mutex_acquired
    ompt_callback_mutex_acquired, ompt_callback_mutex_released
    ompt_callback_mutex_released
    ompt_callback_work
    ompt_callback_dispatch
    ompt_callback_flush

> Note: | The raw OMPT events are used to generate ranges indicating the runtime of OpenMP operations and constructs.

Example screenshot:

## 12. OS Runtime Libraries Trace

OS runtime libraries can be traced to gather information about low-level userspace APIs. This traces the system call wrappers and thread synchronization interfaces exposed by the C runtime and POSIX Threads (pthread) libraries. This does not perform a complete runtime library API trace, but instead focuses on the functions that can take a long time to execute, or could potentially cause your thread be unscheduled from the CPU while waiting for an event to complete.

OS runtime tracing complements and enhances sampling information by:

1. Visualizing when the process is communicating with the hardware, controlling resources, performing multi-threading synchronization or interacting with the kernel scheduler.

2. Adding additional thread states by correlating how OS runtime libraries traces affect the thread scheduling:

   - Waiting — the thread is not scheduled on a CPU, it is inside of an OS runtime libraries trace and is believed to be waiting on the firmware to complete a request.

   - In OS runtime library function — the thread is scheduled on a CPU and inside of an OS runtime libraries trace. If the trace represents a system call, the process is likely running in kernel mode.

3. Collecting backtraces for long OS runtime libraries call. This provides a way to gather blocked-state backtraces, allowing you to gain more context about why the thread was blocked so long, yet avoiding unnecessary overhead for short events.

To enable OS runtime libraries tracing from Nsight Systems:

CLI — Use the `-t`, `--trace` option with the `osrt` parameter. See Command Line Options for more information.

GUI — Select the Collect OS runtime libraries trace checkbox.

You can also use Skip if shorter than. This will skip calls shorter than the given threshold. Enabling this option will improve performances as well as reduce noise on thetimeline. We strongly encourage you to skip OS runtime libraries call shorter than 1 μs.

### 12.1. Locking a Resource

The functions listed below receive a special treatment. If the tool detects that the resource is already acquired by another thread and will induce a blocking call, we always trace it. Otherwise, it will never be traced.

    pthread_mutex_lock
    pthread_rwlock_rdlock
    pthread_rwlock_wrlock
    pthread_spin_lock
    sem_wait

Note that even if a call is determined as potentially blocking, there is a chance that it may not actually block after a few cycles have elapsed. The call will still be traced in this scenario.

### 12.2. Limitations

- Nsight Systems only traces syscall wrappers exposed by the C runtime. It is not able to trace syscall invoked through assembly code.

- Additional thread states, as well as backtrace collection on long calls, are only enabled if sampling is turned on.

- It is not possible to configure the depth and duration threshold when collecting backtraces. Currently, only OS runtime libraries calls longer than 80 μs will generate a backtrace with a maximum of 24 frames. This limitation will be removed in a future version of the product.

- It is required to compile your application and libraries with the `-funwind-tables` compiler flag in order for Nsight Systems to unwind the backtraces correctly.

### 12.3. OS Runtime Libraries Trace Filters

The OS runtime libraries tracing is limited to a select list of functions. It also depends on the version of the C runtime linked to the application.

### 12.4. OS Runtime Default Function List

Libc system call wrappers

    accept
    accept4
    acct
    alarm
    arch_prctl
    bind
    bpf
    brk
    chroot
    clock_nanosleep
    connect
    copy_file_range
    creat
    creat64
    dup
    dup2
    dup3
    epoll_ctl
    epoll_pwait
    epoll_wait
    fallocate
    fallocate64
    fcntl
    fdatasync
    flock
    fork
    fsync
    ftruncate
    futex
    ioctl
    ioperm
    iopl
    kill
    killpg
    listen
    membarrier
    mlock
    mlock2
    mlockall
    mmap
    mmap64
    mount
    move_pages
    mprotect
    mq_notify
    mq_open
    mq_receive
    mq_send
    mq_timedreceive
    mq_timedsend
    mremap
    msgctl
    msgget
    msgrcv
    msgsnd
    msync
    munmap
    nanosleep
    nfsservctl
    open
    open64
    openat
    openat64
    pause
    pipe
    pipe2
    pivot_root
    poll
    ppoll
    prctl
    pread
    pread64
    preadv
    preadv2
    preadv64
    process_vm_readv
    process_vm_writev
    pselect6
    ptrace
    pwrite
    pwrite64
    pwritev
    pwritev2
    pwritev64
    read
    readv
    reboot
    recv
    recvfrom
    recvmmsg
    recvmsg
    rt_sigaction
    rt_sigqueueinfo
    rt_sigsuspend
    rt_sigtimedwait
    sched_yield
    seccomp
    select
    semctl
    semget
    semop
    semtimedop
    send
    sendfile
    sendfile64
    sendmmsg
    sendmsg
    sendto
    shmat
    shmctl
    shmdt
    shmget
    shutdown
    sigaction
    sigsuspend
    sigtimedwait
    socket
    socketpair
    splice
    swapoff
    swapon
    sync
    sync_file_range
    syncfs
    tee
    tgkill
    tgsigqueueinfo
    tkill
    truncate
    umount2
    unshare
    uselib
    vfork
    vhangup
    vmsplice
    wait
    wait3
    wait4
    waitid
    waitpid
    write
    writev
    _sysctl

POSIX Threads

    pthread_barrier_wait
    pthread_cancel
    pthread_cond_broadcast
    pthread_cond_signal
    pthread_cond_timedwait
    pthread_cond_wait
    pthread_create
    pthread_join
    pthread_kill
    pthread_mutex_lock
    pthread_mutex_timedlock
    pthread_mutex_trylock
    pthread_rwlock_rdlock
    pthread_rwlock_timedrdlock
    pthread_rwlock_timedwrlock
    pthread_rwlock_tryrdlock
    pthread_rwlock_trywrlock
    pthread_rwlock_wrlock
    pthread_spin_lock
    pthread_spin_trylock
    pthread_timedjoin_np
    pthread_tryjoin_np
    pthread_yield
    sem_timedwait
    sem_trywait
    sem_wait

I/O

    aio_fsync
    aio_fsync64
    aio_suspend
    aio_suspend64
    fclose
    fcloseall
    fflush
    fflush_unlocked
    fgetc
    fgetc_unlocked
    fgets
    fgets_unlocked
    fgetwc
    fgetwc_unlocked
    fgetws
    fgetws_unlocked
    flockfile
    fopen
    fopen64
    fputc
    fputc_unlocked
    fputs
    fputs_unlocked
    fputwc
    fputwc_unlocked
    fputws
    fputws_unlocked
    fread
    fread_unlocked
    freopen
    freopen64
    ftrylockfile
    fwrite
    fwrite_unlocked
    getc
    getc_unlocked
    getdelim
    getline
    getw
    getwc
    getwc_unlocked
    lockf
    lockf64
    mkfifo
    mkfifoat
    posix_fallocate
    posix_fallocate64
    putc
    putc_unlocked
    putwc
    putwc_unlocked

Miscellaneous

    forkpty
    popen
    posix_spawn
    posix_spawnp
    sigwait
    sigwaitinfo
    sleep
    system
    usleep

## 13. NVTX Trace

The NVIDIA Tools Extension Library (NVTX) is a powerful mechanism that allows users to manually instrument their application. Nsight Systems can then collect the information and present it on the timeline.

Nsight Systems supports version 3.0 of the NVTX specification.

The following features are supported:

- Domains

      nvtxDomainCreate(), nvtxDomainDestroy()

      nvtxDomainRegisterString()

- Push-pop ranges (nested ranges that start and end in the same thread).

      nvtxRangePush(), nvtxRangePushEx()

      nvtxRangePop()

      nvtxDomainRangePushEx()

      nvtxDomainRangePop()

- Start-end ranges (ranges that are global to the process and are not restricted to a single thread)

      nvtxRangeStart(), nvtxRangeStartEx()

      nvtxRangeEnd()

      nvtxDomainRangeStartEx()

      nvtxDomainRangeEnd()

- Marks

      nvtxMark(), nvtxMarkEx()

      nvtxDomainMarkEx()

- Thread names

      nvtxNameOsThread()

- Categories

      nvtxNameCategory()

      nvtxDomainNameCategory()

To learn more about specific features of NVTX, please refer to the NVTX header file: `nvToolsExt.h` or the NVTX documentation.

To use NVTX in your application, follow these steps:

1. Add `#include "nvtx3/nvToolsExt.h"` in your source code. The nvtx3 directory is located in the Nsight Systems package in the Target-<architecture>/nvtx/include directory and is available via github at http://github.com/NVIDIA/NVTX.

2. Add the following compiler flag: `-ldl`

3. Add calls to the NVTX API functions. For example, try adding `nvtxRangePush("main")` in the beginning of the `main()` function, and `nvtxRangePop()` just before the return statement in the end.

   For convenience in C++ code, consider adding a wrapper that implements RAII (resource acquisition is initialization) pattern, which would guarantee that every range gets closed.

4. In the project settings, select the Collect NVTX trace checkbox.

5. If you are on Android target, make sure that your application is launched by Nsight Systems. This is required so that the necessary launch environment is prepared, and the library responsible for collection of NVTX trace data is properly injected into the process.

6. If you are on Linux on Tegra, if launching the application manually, the following environment variables should be specified:

   - For ARMv7 processes:

         NVTX_INJECTION32_PATH=/opt/nvidia/nsight_systems/libToolsInjection32.so

   - For ARMv8 processes:

         NVTX_INJECTION64_PATH=/opt/nvidia/nsight_systems/libToolsInjection64.so

In addition, by enabling the "Insert NVTX Marker hotkey" option it is possible to add NVTX markers to a running non-console applications by pressing the F11 key. These will appear in the report under the NVTX Domain named "HotKey markers".

Typically calls to NVTX functions can be left in the source code even if the application is not being built for profiling purposes, since the overhead is very low when the profiler is not attached.

NVTX is not intended to annotate very small pieces of code that are being called very frequently. A good rule of thumb to use: if code being annotated usually takes less than 1 microsecond to execute, adding an NVTX range around this code should be done carefully.

> Note: | Range annotations should be matched carefully. If many ranges are opened but not closed, Nsight Systems has no meaningful way to visualize it. A rule of thumb is to not have more than a couple dozen ranges open at any point in time. Nsight Systems does not support reports with many unclosed ranges.

## 14. CUDA Trace

Nsight Systems is capable of capturing information about CUDA execution in the profiled process.

The following information can be collected and presented on the timeline in the report:

- CUDA API trace — trace of CUDA Runtime and CUDA Driver calls made by the application.

  - CUDA Runtime calls typically start with `cuda` prefix (e.g. `cudaLaunch`).

  - CUDA Driver calls typically start with `cu` prefix (e.g. `cuDeviceGetCount`).

- CUDA workload trace — trace of activity happening on the GPU, which includes memory operations (e.g., Host-to-Device memory copies) and kernel executions. Within the threads that use the CUDA API, additional child rows will appear in the timeline tree.

- On Nsight Systems Workstation Edition, cuDNN and cuBLAS API tracing and OpenACC tracing.

Near the bottom of the timeline row tree, the GPU node will appear and contain a CUDA node. Within the CUDA node, each CUDA context used within the process will be shown along with its corresponding CUDA streams. Steams will contain memory operations and kernel launches on the GPU. Kernel launches are represented by blue, while memory transfers are displayed in red.

The easiest way to capture CUDA information is to launch the process from Nsight Systems, and it will setup the environment for you. To do so, simply set up a normal launch and select the Collect CUDA trace checkbox.

For Nsight Systems Workstation Edition this looks like:

For Nsight Systems Embedded Platforms Edition this looks like:

Additional configuration parameters are available:

- Collect backtraces for API calls longer than X seconds - turns on collection of CUDA API backtraces and sets the minimum time a CUDA API event must take before its backtraces are collected. Setting this value too low can cause high application overhead and seriously increase the size of your results file.

- Flush data periodically — specifies the period after which an attempt to flush CUDA trace data will be made. Normally, in order to collect full CUDA trace, the application needs to finalize the device used for CUDA work (call `cudaDeviceReset()`, and then let the application gracefully exit (as opposed to crashing).

  This option allows flushing CUDA trace data even before the device is finalized. However, it might introduce additional overhead to a random CUDA Driver or CUDA Runtime API call.

- Skip some API calls — avoids tracing insignificant CUDA Runtime API calls (namely, `cudaConfigureCall()`, `cudaSetupArgument()`, `cudaHostGetDevicePointers()`). Not tracing these functions allows Nsight Systems to significantly reduce the profiling overhead, without losing any interesting data. (See CUDA Trace Filters, below)

- Collect GPU Memory Usage - collects information used to generate a graph of CUDA allocated memory across time. Note that this will increase overhead. See section on CUDA GPU Memory Allocation Graph below.

- Collect Unified Memory CPU page faults - collects information on page faults that occur when CPU code tries to access a memory page that resides on the device. See section on Unified Memory CPU Page Faults in the Unified Memory Transfer Trace documentation below.

- Collect Unified Memory GPU page faults - collects information on page faults that occur when GPU code tries to access a memory page that resides on the CPU. See section on Unified Memory GPU Page Faults in the Unified Memory Transfer Trace documentation below.

- For Nsight Systems Workstation Edition, Collect cuDNN trace, Collect cuBLAS trace, Collect OpenACC trace - selects which (if any) extra libraries that depend on CUDA to trace.

  OpenACC versions 2.0, 2.5, and 2.6 are supported when using PGI runtime version 15.7 or greater and not compiling statically. In order to differentiate constructs, a PGI runtime of 16.1 or later is required. Note that Nsight Systems Workstation Edition does not support the GCC implementation of OpenACC at this time.

- For Nsight Systems Embedded Platforms Edition if desired, the target application can be manually set up to collect CUDA trace. To capture information about CUDA execution, the following requirements should be satisfied:

  - The profiled process should be started with the specified environment variable, depending on the architecture of the process:

    - For ARMv7 (32-bit) processes: `CUDA_INJECTION32_PATH`, which should point to the injection library:

          /opt/nvidia/nsight_systems/libToolsInjection32.so

    - For ARMv8 (64-bit) processes: `CUDA_INJECTION64_PATH`, which should point to the injection library:

          /opt/nvidia/nsight_systems/libToolsInjection64.so

  - If the application is started by Nsight Systems, all required environment variables will be set automatically.

Please note that if your application crashes before all collected CUDA trace data has been copied out, some or all data might be lost and not present in the report.

### 14.1. CUDA GPU Memory Allocation Graph

When the Collect GPU Memory Usage option is selected from the Collect CUDA trace option set, Nsight Systems will track CUDA GPU memory allocations and deallocations and present a graph of this information in the timeline. This is not the same as the GPU memory graph generated during stutter analysis on the Windows target (see Stutter Memory Trace)

Below, in the report on the left, memory is allocated and freed during the collection. In the report on the right, memory is allocated, but not freed during the collection.

Here is another example, where allocations are happening on multiple GPUs

### 14.2. Unified Memory Transfer Trace

For Nsight Systems Workstation Edition, Unified Memory (also called Managed Memory) transfer trace is enabled automatically in Nsight Systems when CUDA trace is selected. It incurs no overhead in programs that do not perform any Unified Memory transfers. Data is displayed in the Managed Memory area of the timeline:

HtoD transfer indicates the CUDA kernel accessed managed memory that was residing on the host, so the kernel execution paused and transferred the data to the device. Heavy traffic here will incur performance penalties in CUDA kernels, so consider using manual cudaMemcpy operations from pinned host memory instead.

PtoP transfer indicates the CUDA kernel accessed managed memory that was residing on a different device, so the kernel execution paused and transferred the data to this device. Heavy traffic here will incur performance penalties, so consider using manual cudaMemcpyPeer operations to transfer from other devices' memory instead. The row showing these events is for the destination device -- the source device is shown in the tooltip for each transfer event.

DtoH transfer indicates the CPU accessed managed memory that was residing on a CUDA device, so the CPU execution paused and transferred the data to system memory. Heavy traffic here will incur performance penalties in CPU code, so consider using manual cudaMemcpy operations from pinned host memory instead.

Some Unified Memory transfers are highlighted with red to indicate potential performance issues:

Transfers with the following migration causes are highlighted:

- Coherence

  Unified Memory migration occurred to guarantee data coherence. SMs (streaming multiprocessors) stop until the migration completes.

- Eviction

  Unified Memory migrated to the CPU because it was evicted to make room for another block of memory on the GPU. This happens due to memory overcommitment which is available on Linux with Compute Capability ≥ 6.

### Unified Memory CPU Page Faults

The Unified Memory CPU page faults feature in Nsight Systems tracks the page faults that occur when CPU code tries to access a memory page that resides on the device.

> Note: | Collecting Unified Memory CPU page faults can cause overhead of up to 70% in testing. Please use this functionality only when needed.

### Unified Memory GPU Page Faults

The Unified Memory GPU page faults feature in Nsight Systems tracks the page faults that occur when GPU code tries to access a memory page that resides on the host.

> Note: | Collecting Unified Memory GPU page faults can cause overhead of up to 70% in testing. Please use this functionality only when needed.

### 14.3. CUDA Default Function List for CLI

CUDA Runtime API

    cudaBindSurfaceToArray
    cudaBindTexture
    cudaBindTexture2D
    cudaBindTextureToArray
    cudaBindTextureToMipmappedArray
    cudaConfigureCall
    cudaCreateSurfaceObject
    cudaCreateTextureObject
    cudaD3D10MapResources
    cudaD3D10RegisterResource
    cudaD3D10UnmapResources
    cudaD3D10UnregisterResource
    cudaD3D9MapResources
    cudaD3D9MapVertexBuffer
    cudaD3D9RegisterResource
    cudaD3D9RegisterVertexBuffer
    cudaD3D9UnmapResources
    cudaD3D9UnmapVertexBuffer
    cudaD3D9UnregisterResource
    cudaD3D9UnregisterVertexBuffer
    cudaDestroySurfaceObject
    cudaDestroyTextureObject
    cudaDeviceReset
    cudaDeviceSynchronize
    cudaEGLStreamConsumerAcquireFrame
    cudaEGLStreamConsumerConnect
    cudaEGLStreamConsumerConnectWithFlags
    cudaEGLStreamConsumerDisconnect
    cudaEGLStreamConsumerReleaseFrame
    cudaEGLStreamConsumerReleaseFrame
    cudaEGLStreamProducerConnect
    cudaEGLStreamProducerDisconnect
    cudaEGLStreamProducerReturnFrame
    cudaEventCreate
    cudaEventCreateFromEGLSync
    cudaEventCreateWithFlags
    cudaEventDestroy
    cudaEventQuery
    cudaEventRecord
    cudaEventRecord_ptsz
    cudaEventSynchronize
    cudaFree
    cudaFreeArray
    cudaFreeHost
    cudaFreeMipmappedArray
    cudaGLMapBufferObject
    cudaGLMapBufferObjectAsync
    cudaGLRegisterBufferObject
    cudaGLUnmapBufferObject
    cudaGLUnmapBufferObjectAsync
    cudaGLUnregisterBufferObject
    cudaGraphicsD3D10RegisterResource
    cudaGraphicsD3D11RegisterResource
    cudaGraphicsD3D9RegisterResource
    cudaGraphicsEGLRegisterImage
    cudaGraphicsGLRegisterBuffer
    cudaGraphicsGLRegisterImage
    cudaGraphicsMapResources
    cudaGraphicsUnmapResources
    cudaGraphicsUnregisterResource
    cudaGraphicsVDPAURegisterOutputSurface
    cudaGraphicsVDPAURegisterVideoSurface
    cudaHostAlloc
    cudaHostRegister
    cudaHostUnregister
    cudaLaunch
    cudaLaunchCooperativeKernel
    cudaLaunchCooperativeKernelMultiDevice
    cudaLaunchCooperativeKernel_ptsz
    cudaLaunchKernel
    cudaLaunchKernel_ptsz
    cudaLaunch_ptsz
    cudaMalloc
    cudaMalloc3D
    cudaMalloc3DArray
    cudaMallocArray
    cudaMallocHost
    cudaMallocManaged
    cudaMallocMipmappedArray
    cudaMallocPitch
    cudaMemGetInfo
    cudaMemPrefetchAsync
    cudaMemPrefetchAsync_ptsz
    cudaMemcpy
    cudaMemcpy2D
    cudaMemcpy2DArrayToArray
    cudaMemcpy2DArrayToArray_ptds
    cudaMemcpy2DAsync
    cudaMemcpy2DAsync_ptsz
    cudaMemcpy2DFromArray
    cudaMemcpy2DFromArrayAsync
    cudaMemcpy2DFromArrayAsync_ptsz
    cudaMemcpy2DFromArray_ptds
    cudaMemcpy2DToArray
    cudaMemcpy2DToArrayAsync
    cudaMemcpy2DToArrayAsync_ptsz
    cudaMemcpy2DToArray_ptds
    cudaMemcpy2D_ptds
    cudaMemcpy3D
    cudaMemcpy3DAsync
    cudaMemcpy3DAsync_ptsz
    cudaMemcpy3DPeer
    cudaMemcpy3DPeerAsync
    cudaMemcpy3DPeerAsync_ptsz
    cudaMemcpy3DPeer_ptds
    cudaMemcpy3D_ptds
    cudaMemcpyArrayToArray
    cudaMemcpyArrayToArray_ptds
    cudaMemcpyAsync
    cudaMemcpyAsync_ptsz
    cudaMemcpyFromArray
    cudaMemcpyFromArrayAsync
    cudaMemcpyFromArrayAsync_ptsz
    cudaMemcpyFromArray_ptds
    cudaMemcpyFromSymbol
    cudaMemcpyFromSymbolAsync
    cudaMemcpyFromSymbolAsync_ptsz
    cudaMemcpyFromSymbol_ptds
    cudaMemcpyPeer
    cudaMemcpyPeerAsync
    cudaMemcpyToArray
    cudaMemcpyToArrayAsync
    cudaMemcpyToArrayAsync_ptsz
    cudaMemcpyToArray_ptds
    cudaMemcpyToSymbol
    cudaMemcpyToSymbolAsync
    cudaMemcpyToSymbolAsync_ptsz
    cudaMemcpyToSymbol_ptds
    cudaMemcpy_ptds
    cudaMemset
    cudaMemset2D
    cudaMemset2DAsync
    cudaMemset2DAsync_ptsz
    cudaMemset2D_ptds
    cudaMemset3D
    cudaMemset3DAsync
    cudaMemset3DAsync_ptsz
    cudaMemset3D_ptds
    cudaMemsetAsync
    cudaMemsetAsync_ptsz
    cudaMemset_ptds
    cudaPeerRegister
    cudaPeerUnregister
    cudaStreamAddCallback
    cudaStreamAddCallback_ptsz
    cudaStreamAttachMemAsync
    cudaStreamAttachMemAsync_ptsz
    cudaStreamCreate
    cudaStreamCreateWithFlags
    cudaStreamCreateWithPriority
    cudaStreamDestroy
    cudaStreamQuery
    cudaStreamQuery_ptsz
    cudaStreamSynchronize
    cudaStreamSynchronize_ptsz
    cudaStreamWaitEvent
    cudaStreamWaitEvent_ptsz
    cudaThreadSynchronize
    cudaUnbindTexture

CUDA Primary API

    cu64Array3DCreate
    cu64ArrayCreate
    cu64D3D9MapVertexBuffer
    cu64GLMapBufferObject
    cu64GLMapBufferObjectAsync
    cu64MemAlloc
    cu64MemAllocPitch
    cu64MemFree
    cu64MemGetInfo
    cu64MemHostAlloc
    cu64Memcpy2D
    cu64Memcpy2DAsync
    cu64Memcpy2DUnaligned
    cu64Memcpy3D
    cu64Memcpy3DAsync
    cu64MemcpyAtoD
    cu64MemcpyDtoA
    cu64MemcpyDtoD
    cu64MemcpyDtoDAsync
    cu64MemcpyDtoH
    cu64MemcpyDtoHAsync
    cu64MemcpyHtoD
    cu64MemcpyHtoDAsync
    cu64MemsetD16
    cu64MemsetD16Async
    cu64MemsetD2D16
    cu64MemsetD2D16Async
    cu64MemsetD2D32
    cu64MemsetD2D32Async
    cu64MemsetD2D8
    cu64MemsetD2D8Async
    cu64MemsetD32
    cu64MemsetD32Async
    cu64MemsetD8
    cu64MemsetD8Async
    cuArray3DCreate
    cuArray3DCreate_v2
    cuArrayCreate
    cuArrayCreate_v2
    cuArrayDestroy
    cuBinaryFree
    cuCompilePtx
    cuCtxCreate
    cuCtxCreate_v2
    cuCtxDestroy
    cuCtxDestroy_v2
    cuCtxSynchronize
    cuD3D10CtxCreate
    cuD3D10CtxCreateOnDevice
    cuD3D10CtxCreate_v2
    cuD3D10MapResources
    cuD3D10RegisterResource
    cuD3D10UnmapResources
    cuD3D10UnregisterResource
    cuD3D11CtxCreate
    cuD3D11CtxCreateOnDevice
    cuD3D11CtxCreate_v2
    cuD3D9CtxCreate
    cuD3D9CtxCreateOnDevice
    cuD3D9CtxCreate_v2
    cuD3D9MapResources
    cuD3D9MapVertexBuffer
    cuD3D9MapVertexBuffer_v2
    cuD3D9RegisterResource
    cuD3D9RegisterVertexBuffer
    cuD3D9UnmapResources
    cuD3D9UnmapVertexBuffer
    cuD3D9UnregisterResource
    cuD3D9UnregisterVertexBuffer
    cuEGLStreamConsumerAcquireFrame
    cuEGLStreamConsumerConnect
    cuEGLStreamConsumerConnectWithFlags
    cuEGLStreamConsumerDisconnect
    cuEGLStreamConsumerReleaseFrame
    cuEGLStreamProducerConnect
    cuEGLStreamProducerDisconnect
    cuEGLStreamProducerPresentFrame
    cuEGLStreamProducerReturnFrame
    cuEventCreate
    cuEventCreateFromEGLSync
    cuEventCreateFromNVNSync
    cuEventDestroy
    cuEventDestroy_v2
    cuEventQuery
    cuEventRecord
    cuEventRecord_ptsz
    cuEventSynchronize
    cuGLCtxCreate
    cuGLCtxCreate_v2
    cuGLInit
    cuGLMapBufferObject
    cuGLMapBufferObjectAsync
    cuGLMapBufferObjectAsync_v2
    cuGLMapBufferObjectAsync_v2_ptsz
    cuGLMapBufferObject_v2
    cuGLMapBufferObject_v2_ptds
    cuGLRegisterBufferObject
    cuGLUnmapBufferObject
    cuGLUnmapBufferObjectAsync
    cuGLUnregisterBufferObject
    cuGraphicsD3D10RegisterResource
    cuGraphicsD3D11RegisterResource
    cuGraphicsD3D9RegisterResource
    cuGraphicsEGLRegisterImage
    cuGraphicsGLRegisterBuffer
    cuGraphicsGLRegisterImage
    cuGraphicsMapResources
    cuGraphicsMapResources_ptsz
    cuGraphicsUnmapResources
    cuGraphicsUnmapResources_ptsz
    cuGraphicsUnregisterResource
    cuGraphicsVDPAURegisterOutputSurface
    cuGraphicsVDPAURegisterVideoSurface
    cuInit
    cuLaunch
    cuLaunchCooperativeKernel
    cuLaunchCooperativeKernelMultiDevice
    cuLaunchCooperativeKernel_ptsz
    cuLaunchGrid
    cuLaunchGridAsync
    cuLaunchKernel
    cuLaunchKernel_ptsz
    cuLinkComplete
    cuLinkCreate
    cuLinkCreate_v2
    cuLinkDestroy
    cuMemAlloc
    cuMemAllocHost
    cuMemAllocHost_v2
    cuMemAllocManaged
    cuMemAllocPitch
    cuMemAllocPitch_v2
    cuMemAlloc_v2
    cuMemFree
    cuMemFreeHost
    cuMemFree_v2
    cuMemGetInfo
    cuMemGetInfo_v2
    cuMemHostAlloc
    cuMemHostAlloc_v2
    cuMemHostRegister
    cuMemHostRegister_v2
    cuMemHostUnregister
    cuMemPeerRegister
    cuMemPeerUnregister
    cuMemPrefetchAsync
    cuMemPrefetchAsync_ptsz
    cuMemcpy
    cuMemcpy2D
    cuMemcpy2DAsync
    cuMemcpy2DAsync_v2
    cuMemcpy2DAsync_v2_ptsz
    cuMemcpy2DUnaligned
    cuMemcpy2DUnaligned_v2
    cuMemcpy2DUnaligned_v2_ptds
    cuMemcpy2D_v2
    cuMemcpy2D_v2_ptds
    cuMemcpy3D
    cuMemcpy3DAsync
    cuMemcpy3DAsync_v2
    cuMemcpy3DAsync_v2_ptsz
    cuMemcpy3DPeer
    cuMemcpy3DPeerAsync
    cuMemcpy3DPeerAsync_ptsz
    cuMemcpy3DPeer_ptds
    cuMemcpy3D_v2
    cuMemcpy3D_v2_ptds
    cuMemcpyAsync
    cuMemcpyAsync_ptsz
    cuMemcpyAtoA
    cuMemcpyAtoA_v2
    cuMemcpyAtoA_v2_ptds
    cuMemcpyAtoD
    cuMemcpyAtoD_v2
    cuMemcpyAtoD_v2_ptds
    cuMemcpyAtoH
    cuMemcpyAtoHAsync
    cuMemcpyAtoHAsync_v2
    cuMemcpyAtoHAsync_v2_ptsz
    cuMemcpyAtoH_v2
    cuMemcpyAtoH_v2_ptds
    cuMemcpyDtoA
    cuMemcpyDtoA_v2
    cuMemcpyDtoA_v2_ptds
    cuMemcpyDtoD
    cuMemcpyDtoDAsync
    cuMemcpyDtoDAsync_v2
    cuMemcpyDtoDAsync_v2_ptsz
    cuMemcpyDtoD_v2
    cuMemcpyDtoD_v2_ptds
    cuMemcpyDtoH
    cuMemcpyDtoHAsync
    cuMemcpyDtoHAsync_v2
    cuMemcpyDtoHAsync_v2_ptsz
    cuMemcpyDtoH_v2
    cuMemcpyDtoH_v2_ptds
    cuMemcpyHtoA
    cuMemcpyHtoAAsync
    cuMemcpyHtoAAsync_v2
    cuMemcpyHtoAAsync_v2_ptsz
    cuMemcpyHtoA_v2
    cuMemcpyHtoA_v2_ptds
    cuMemcpyHtoD
    cuMemcpyHtoDAsync
    cuMemcpyHtoDAsync_v2
    cuMemcpyHtoDAsync_v2_ptsz
    cuMemcpyHtoD_v2
    cuMemcpyHtoD_v2_ptds
    cuMemcpyPeer
    cuMemcpyPeerAsync
    cuMemcpyPeerAsync_ptsz
    cuMemcpyPeer_ptds
    cuMemcpy_ptds
    cuMemcpy_v2
    cuMemsetD16
    cuMemsetD16Async
    cuMemsetD16Async_ptsz
    cuMemsetD16_v2
    cuMemsetD16_v2_ptds
    cuMemsetD2D16
    cuMemsetD2D16Async
    cuMemsetD2D16Async_ptsz
    cuMemsetD2D16_v2
    cuMemsetD2D16_v2_ptds
    cuMemsetD2D32
    cuMemsetD2D32Async
    cuMemsetD2D32Async_ptsz
    cuMemsetD2D32_v2
    cuMemsetD2D32_v2_ptds
    cuMemsetD2D8
    cuMemsetD2D8Async
    cuMemsetD2D8Async_ptsz
    cuMemsetD2D8_v2
    cuMemsetD2D8_v2_ptds
    cuMemsetD32
    cuMemsetD32Async
    cuMemsetD32Async_ptsz
    cuMemsetD32_v2
    cuMemsetD32_v2_ptds
    cuMemsetD8
    cuMemsetD8Async
    cuMemsetD8Async_ptsz
    cuMemsetD8_v2
    cuMemsetD8_v2_ptds
    cuMipmappedArrayCreate
    cuMipmappedArrayDestroy
    cuModuleLoad
    cuModuleLoadData
    cuModuleLoadDataEx
    cuModuleLoadFatBinary
    cuModuleUnload
    cuStreamAddCallback
    cuStreamAddCallback_ptsz
    cuStreamAttachMemAsync
    cuStreamAttachMemAsync_ptsz
    cuStreamBatchMemOp
    cuStreamBatchMemOp_ptsz
    cuStreamCreate
    cuStreamCreateWithPriority
    cuStreamDestroy
    cuStreamDestroy_v2
    cuStreamSynchronize
    cuStreamSynchronize_ptsz
    cuStreamWaitEvent
    cuStreamWaitEvent_ptsz
    cuStreamWaitValue32
    cuStreamWaitValue32_ptsz
    cuStreamWaitValue64
    cuStreamWaitValue64_ptsz
    cuStreamWriteValue32
    cuStreamWriteValue32_ptsz
    cuStreamWriteValue64
    cuStreamWriteValue64_ptsz
    cuSurfObjectCreate
    cuSurfObjectDestroy
    cuSurfRefCreate
    cuSurfRefDestroy
    cuTexObjectCreate
    cuTexObjectDestroy
    cuTexRefCreate
    cuTexRefDestroy
    cuVDPAUCtxCreate
    cuVDPAUCtxCreate_v2

### 14.4. cuDNN Function List for X86 CLI

cuDNN API functions

    cudnnActivationBackward
    cudnnActivationBackward_v3
    cudnnActivationBackward_v4
    cudnnActivationForward
    cudnnActivationForward_v3
    cudnnActivationForward_v4
    cudnnAddTensor
    cudnnBatchNormalizationBackward
    cudnnBatchNormalizationBackwardEx
    cudnnBatchNormalizationForwardInference
    cudnnBatchNormalizationForwardTraining
    cudnnBatchNormalizationForwardTrainingEx
    cudnnCTCLoss
    cudnnConvolutionBackwardBias
    cudnnConvolutionBackwardData
    cudnnConvolutionBackwardFilter
    cudnnConvolutionBiasActivationForward
    cudnnConvolutionForward
    cudnnCreate
    cudnnCreateAlgorithmPerformance
    cudnnDestroy
    cudnnDestroyAlgorithmPerformance
    cudnnDestroyPersistentRNNPlan
    cudnnDivisiveNormalizationBackward
    cudnnDivisiveNormalizationForward
    cudnnDropoutBackward
    cudnnDropoutForward
    cudnnDropoutGetReserveSpaceSize
    cudnnDropoutGetStatesSize
    cudnnFindConvolutionBackwardDataAlgorithm
    cudnnFindConvolutionBackwardDataAlgorithmEx
    cudnnFindConvolutionBackwardFilterAlgorithm
    cudnnFindConvolutionBackwardFilterAlgorithmEx
    cudnnFindConvolutionForwardAlgorithm
    cudnnFindConvolutionForwardAlgorithmEx
    cudnnFindRNNBackwardDataAlgorithmEx
    cudnnFindRNNBackwardWeightsAlgorithmEx
    cudnnFindRNNForwardInferenceAlgorithmEx
    cudnnFindRNNForwardTrainingAlgorithmEx
    cudnnFusedOpsExecute
    cudnnIm2Col
    cudnnLRNCrossChannelBackward
    cudnnLRNCrossChannelForward
    cudnnMakeFusedOpsPlan
    cudnnMultiHeadAttnBackwardData
    cudnnMultiHeadAttnBackwardWeights
    cudnnMultiHeadAttnForward
    cudnnOpTensor
    cudnnPoolingBackward
    cudnnPoolingForward
    cudnnRNNBackwardData
    cudnnRNNBackwardDataEx
    cudnnRNNBackwardWeights
    cudnnRNNBackwardWeightsEx
    cudnnRNNForwardInference
    cudnnRNNForwardInferenceEx
    cudnnRNNForwardTraining
    cudnnRNNForwardTrainingEx
    cudnnReduceTensor
    cudnnReorderFilterAndBias
    cudnnRestoreAlgorithm
    cudnnRestoreDropoutDescriptor
    cudnnSaveAlgorithm
    cudnnScaleTensor
    cudnnSoftmaxBackward
    cudnnSoftmaxForward
    cudnnSpatialTfGridGeneratorBackward
    cudnnSpatialTfGridGeneratorForward
    cudnnSpatialTfSamplerBackward
    cudnnSpatialTfSamplerForward
    cudnnTransformFilter
    cudnnTransformTensor
    cudnnTransformTensorEx

## 15. OpenACC Trace

Nsight Systems for Linux x86_64 and Power targets is capable of capturing information about OpenACC execution in the profiled process.

OpenACC versions 2.0, 2.5, and 2.6 are supported when using PGI runtime version 15.7 or later. In order to differentiate constructs (see tooltip below), a PGI runtime of 16.0 or later is required. Note that Nsight Systems does not support the GCC implementation of OpenACC at this time.

Under the CPU rows in the timeline tree, each thread that uses OpenACC will show OpenACC trace information. You can click on a OpenACC API call to see correlation with the underlying CUDA API calls (highlighted in teal):

If the OpenACC API results in GPU work, that will also be highlighted:

Hovering over a particular OpenACC construct will bring up a tooltip with details about that construct:

To capture OpenACC information from the Nsight Systems GUI, select the Collect OpenACC trace checkbox under Collect CUDA trace configurations. Note that turning on OpenACC tracing will also turn on CUDA tracing.

Please note that if your application crashes before all collected OpenACC trace data has been copied out, some or all data might be lost and not present in the report.

## 16. OpenGL Trace

OpenGL and OpenGL ES APIs can be traced to assist in the analysis of CPU and GPU interactions.

A few usage examples are:

1. Visualize how long `eglSwapBuffers` (or similar) is taking.

2. API trace can easily show correlations between thread state and graphics driver's behavior, uncovering where the CPU may be waiting on the GPU.

3. Spot bubbles of opportunity on the GPU, where more GPU workload could be created.

4. Use `KHR_debug` extension to trace GL events on both the CPU and GPU.

OpenGL trace feature in Nsight Systems consists of two different activities which will be shown in the CPU rows for those threads

- CPU trace: interception of API calls that an application does to APIs (such as OpenGL, OpenGL ES, EGL, GLX, WGL, etc.).

- GPU trace (or workload trace): trace of GPU workload (activity) triggered by use of OpenGL or OpenGL ES. Since draw calls are executed back-to-back, the GPU workload trace ranges include many OpenGL draw calls and operations in order to optimize performance overhead, rather than tracing each individual operation.

To collect GPU trace, the `glQueryCounter()` function is used to measure how much time batches of GPU workload take to complete.

Ranges defined by the `KHR_debug` calls are represented similarly to OpenGL API and OpenGL GPU workload trace. GPU ranges in this case represent incremental draw cost. They cannot fully account for GPUs that can execute multiple draw calls in parallel. In this case, Nsight Systems will not show overlapping GPU ranges.

### 16.1. OpenGL Trace Using Command Line

For general information on using the target CLI, see CLI Profiling on Linux. For the CLI, the functions that are traced are set to the following list:

    glWaitSync
    glReadPixels
    glReadnPixelsKHR
    glReadnPixelsEXT
    glReadnPixelsARB
    glReadnPixels
    glFlush
    glFinishFenceNV
    glFinish
    glClientWaitSync
    glClearTexSubImage
    glClearTexImage
    glClearStencil
    glClearNamedFramebufferuiv
    glClearNamedFramebufferiv
    glClearNamedFramebufferfv
    glClearNamedFramebufferfi
    glClearNamedBufferSubDataEXT
    glClearNamedBufferSubData
    glClearNamedBufferDataEXT
    glClearNamedBufferData
    glClearIndex
    glClearDepthx
    glClearDepthf
    glClearDepthdNV
    glClearDepth
    glClearColorx
    glClearColorIuiEXT
    glClearColorIiEXT
    glClearColor
    glClearBufferuiv
    glClearBufferSubData
    glClearBufferiv
    glClearBufferfv
    glClearBufferfi
    glClearBufferData
    glClearAccum
    glClear
    glDispatchComputeIndirect
    glDispatchComputeGroupSizeARB
    glDispatchCompute
    glComputeStreamNV
    glNamedFramebufferDrawBuffers
    glNamedFramebufferDrawBuffer
    glMultiDrawElementsIndirectEXT
    glMultiDrawElementsIndirectCountARB
    glMultiDrawElementsIndirectBindlessNV
    glMultiDrawElementsIndirectBindlessCountNV
    glMultiDrawElementsIndirectAMD
    glMultiDrawElementsIndirect
    glMultiDrawElementsEXT
    glMultiDrawElementsBaseVertex
    glMultiDrawElements
    glMultiDrawArraysIndirectEXT
    glMultiDrawArraysIndirectCountARB
    glMultiDrawArraysIndirectBindlessNV
    glMultiDrawArraysIndirectBindlessCountNV
    glMultiDrawArraysIndirectAMD
    glMultiDrawArraysIndirect
    glMultiDrawArraysEXT
    glMultiDrawArrays
    glListDrawCommandsStatesClientNV
    glFramebufferDrawBuffersEXT
    glFramebufferDrawBufferEXT
    glDrawTransformFeedbackStreamInstanced
    glDrawTransformFeedbackStream
    glDrawTransformFeedbackNV
    glDrawTransformFeedbackInstancedEXT
    glDrawTransformFeedbackInstanced
    glDrawTransformFeedbackEXT
    glDrawTransformFeedback
    glDrawTexxvOES
    glDrawTexxOES
    glDrawTextureNV
    glDrawTexsvOES
    glDrawTexsOES
    glDrawTexivOES
    glDrawTexiOES
    glDrawTexfvOES
    glDrawTexfOES
    glDrawRangeElementsEXT
    glDrawRangeElementsBaseVertexOES
    glDrawRangeElementsBaseVertexEXT
    glDrawRangeElementsBaseVertex
    glDrawRangeElements
    glDrawPixels
    glDrawElementsInstancedNV
    glDrawElementsInstancedEXT
    glDrawElementsInstancedBaseVertexOES
    glDrawElementsInstancedBaseVertexEXT
    glDrawElementsInstancedBaseVertexBaseInstanceEXT
    glDrawElementsInstancedBaseVertexBaseInstance
    glDrawElementsInstancedBaseVertex
    glDrawElementsInstancedBaseInstanceEXT
    glDrawElementsInstancedBaseInstance
    glDrawElementsInstancedARB
    glDrawElementsInstanced
    glDrawElementsIndirect
    glDrawElementsBaseVertexOES
    glDrawElementsBaseVertexEXT
    glDrawElementsBaseVertex
    glDrawElements
    glDrawCommandsStatesNV
    glDrawCommandsStatesAddressNV
    glDrawCommandsNV
    glDrawCommandsAddressNV
    glDrawBuffersNV
    glDrawBuffersATI
    glDrawBuffersARB
    glDrawBuffers
    glDrawBuffer
    glDrawArraysInstancedNV
    glDrawArraysInstancedEXT
    glDrawArraysInstancedBaseInstanceEXT
    glDrawArraysInstancedBaseInstance
    glDrawArraysInstancedARB
    glDrawArraysInstanced
    glDrawArraysIndirect
    glDrawArraysEXT
    glDrawArrays
    eglSwapBuffersWithDamageKHR
    eglSwapBuffers
    glXSwapBuffers
    glXQueryDrawable
    glXGetCurrentReadDrawable
    glXGetCurrentDrawable
    glGetQueryObjectuivEXT
    glGetQueryObjectuivARB
    glGetQueryObjectuiv
    glGetQueryObjectivARB
    glGetQueryObjectiv

## 17. Custom ETW Trace

Use the custom ETW trace feature to enable and collect any manifest-based ETW log. The collected events are displayed on the timeline on dedicated rows for each event type.

Custom ETW is available on Windows target machines.

To retain the .etl trace files captured, so that they can be viewed in other tools (e.g. GPUView), change the "Save ETW log files in project folder" option under "Profile Behavior" in Nsight Systems's global Options dialog. The .etl files will appear in the same folder as the .qdrep file, accessible by right-clicking the report in the Project Explorer and choosing "Show in Folder...". Data collected from each ETW provider will appear in its own .etl file, and an additional .etl file named "Report XX-Merged-*.etl", containing the events from all captured sources, will be created as well.

## GPU Metric Sampling

### Overview

GPU performance metrics sampling is intended to identify performance limiters in applications using GPU for computations and graphics. It uses periodic sampling to gather performance metrics and detailed timing statistics associated with different GPU hardware units taking advantage of specialized hardware to capture this data in a single pass with minimal overhead.

These metrics provide an overview of GPU efficiency over time within compute, graphics, and input/output (IO) activities such as:

- IO throughputs: PCIe, NVLink, and GPU memory bandwidth
- SM utilization: SMs activity, tensor core activity, instructions issued, warp occupancy, and unassigned warp slots

It is designed to help users answer the common questions:

- Is my GPU idle?
- Is my GPU full? Enough kernel grids size and streams? Are my SMs and warp slots full?
- Am I using TensorCores?
- Is my instruction rate high?
- Am I possibly blocked on IO, or number of warps, etc

Nsight Systems GPU metric sampling is only available for Linux targets on x86-64 and for Windows targets. It requires NVIDIA Turing architecture or newer with minimum driver version r460.

Note:Elevated permissions are required. On Linux use sudo to elevate privileges. On Windows the user must run from an admin command prompt or accept the UAC escalation dialog. See Permissions Issues and Performance Counters for more information.

### Launching GPU Metric Sampling from the GUI

For commands to launch GPU metric sampling from the CLI with examples, see the CLI documentation.

When launching analysis in Nsight Systems, select Collect GPU Metrics.

Select the GPUs dropdown to pick which GPUs you wish to sample.

Select the Metric set: dropdown to choose which available metric set you would like to sample.

Note that metric sets for GPUs that are not being sampled will be greyed out.

### Available Metrics

- GPC Clock Frequency - `gpc__cycles_elapsed.avg.per_second`

  The average GPC clock frequency in hertz. In public documentation the GPC clock may be called the "Application" clock, "Graphic" clock, "Base" clock, or "Boost" clock.

  Note: The collection mechanism for GPC can result in a small fluctuation between samples.

- SYS Clock Frequency - `sys__cycles_elapsed.avg.per_second`

  The average SYS clock frequency in hertz. The GPU front end (command processor), copy engines, and the performance monitor run at the SYS clock. On Turing and NVIDIA GA100 GPUs the GPU metrics sampling frequency is based upon a period of SYS clocks (not time) so samples per second will vary with SYS clock. On NVIDIA GA10x GPUs the GPU metrics sampling rate is based upon a fixed frequency clock. The maximum sampling rate scales linearly with the SYS clock.

- GR Active - `gr__cycles_active.sum.pct_of_peak_sustained_elapsed`

  The percentage of cycles the graphics/compute engine is active. The graphics/compute engine is active if there is any work in the graphics pipe or if the compute pipe is processing work.

  GA100 MIG - MIG is not yet supported. This counter will report the activity of the primary GR engine.

- Sync Compute In Flight - `gr__dispatch_cycles_active_queue_sync.avg.pct_of_peak_sustained_elapsed`

  The percentage of cycles with synchronous compute in flight.

  CUDA: CUDA will only report synchronous queue in the case of MPS configured with 64 sub-context. Synchronous refers to work submitted in VEID=0.

  Graphics: This will be true if any compute work submitted from the direct queue is in flight.

- Async Compute in Flight - `gr__dispatch_cycles_active_queue_async.avg.pct_of_peak_sustained_elapsed`

  The percentage of cycles with asynchronous compute in flight.

  CUDA: CUDA will only report all compute work as asynchronous. The one exception is if MPS is configured and all 64 sub-context are in use. 1 sub-context (VEID=0) will report as synchronous.

  Graphics: This will be true if any compute work submitted from a compute queue is in flight.

- Draw Started - `fe__draw_count.avg.pct_of_peak_sustained_elapsed`

  The ratio of draw calls issued to the graphics pipe to the maximum sustained rate of the graphics pipe.

  Note:The percentage will always be very low as the front end can issue draw calls significantly faster than the pipe can execute the draw call. The rendering of this row will be changed to help indicate when draw calls are being issued.

- Dispatch Started - `gr__dispatch_count.avg.pct_of_peak_sustained_elapsed`

  The ratio of compute grid launches (dispatches) to the compute pipe to the maximum sustained rate of the compute pipe.

  Note: The percentage will always be very low as the front end can issue grid launches significantly faster than the pipe can execute the draw call. The rendering of this row will be changed to help indicate when grid launches are being issued.

- Vertex/Tess/Geometry Warps in Flight - `tpc__warps_active_shader_vtg_realtime.avg.pct_of_peak_sustained_elapsed`

  The ratio of active vertex, geometry, tessellation, and meshlet shader warps resident on the SMs to the maximum number of warps per SM as a percentage.

- Pixel Warps in Flight - `tpc__warps_active_shader_ps_realtime.avg.pct_of_peak_sustained_elapsed`

  The ratio of active pixel/fragment shader warps resident on the SMs to the maximum number of warps per SM as a percentage.

- Compute Warps in Flight - `tpc__warps_active_shader_cs_realtime.avg.pct_of_peak_sustained_elapsed`

  The ratio of active compute shader warps resident on the SMs to the maximum number of warps per SM as a percentage.

- Active SM Unused Warp Slots - `tpc__warps_inactive_sm_active_realtime.avg.pct_of_peak_sustained_elapsed`

  The ratio of inactive warp slots on the SMs to the maximum number of warps per SM as a percentage. This is an indication of how many more warps may fit on the SMs if occupancy is not limited by a resource such as max warps of a shader type, shared memory, registers per thread, or thread blocks per SM.

- Idle SM Unused Warp Slots - `tpc__warps_inactive_sm_idle_realtime.avg.pct_of_peak_sustained_elapsed`

  The ratio of inactive warps slots due to idle SMs to the the maximum number of warps per SM as a percentage.

  This is an indicator that the current workload on the SM is not sufficient to put work on all SMs. This can be due to:
  - CPU starving the GPU
  - current work is too small to saturate the GPU
  - current work is trailing off but blocking next work
- SM Active - `sm__cycles_active.avg.pct_of_peak_sustained_elapsed`

  The ratio of cycles SMs had at least 1 warp in flight (allocated on SM) to the number of cycles as a percentage. A value of 0 indicates all SMs were idle (no warps in flight). A value of 50% can indicate some gradient between all SMs active 50% of the sample period or 50% of SMs active 100% of the sample period.

- SM Issue - `sm__inst_executed_realtime.avg.pct_of_peak_sustained_elapsed`

  The ratio of cyclesthat SM sub-partitions (warp schedulers) issued an instruction to the number of cycles in the sample period as a percentage.

- Tensor Active - `sm__pipe_tensor_cycles_active_realtime.avg.pct_of_peak_sustained_elapsed`

  The ratio of cycles the SM tensor pipes were active issuing tensor instructions to the number of cycles in the sample period as a percentage.

  TU102/4/6: This metric is not available on TU10x for periodic sampling. Please see Tensor Active/FP16 Active.

- Tensor Active / FP16 Active - `sm__pipe_shared_cycles_active_realtime.avg.pct_of_peak_sustained_elapsed`

  TU102/4/6 only

  The ratio of cycles the SM tensor pipes or FP16x2 pipes were active issuing tensor instructions to the number of cycles in the sample period as a percentage.

- VRAM Bandwidth - `dram__throughput.avg.pct_of_peak_sustained_elapsed`

  The ratio of cycles the GPU device memory controllers were actively performing read or write operations to the number of cycles in the sample period as a percentage.

- NVLINK bytes received - `nvlrx__bytes.avg.pct_of_peak_sustained_elapsed`

  The ratio of bytes received on the NVLINK interface to the maximum number of bytes receivable in the sample period as a percentage. This value includes protocol overhead.

- NVLINK bytes transmitted - `nvltx__bytes.avg.pct_of_peak_sustained_elapsed`

  The ratio of bytes transmitted on the NVLINK interface to the maximum number of bytes transmittable in the sample period as a percentage. This value includes protocol overhead.

- PCIe Read Throughput - `pcie__read_bytes.avg.pct_of_peak_sustained_elapsed`

  The ratio of bytes received on the PCIe interface to the maximum number of bytes receivable in the sample period as a percentage. The theoretical value is calculated based upon the PCIe generation and number of lanes. This value includes protocol overhead.

- PCIe Write Throughput - `pcie__write_bytes.avg.pct_of_peak_sustained_elapsed`

  The ratio of bytes received on the PCIe interface to the maximum number of bytes receivable in the sample period as a percentage. The theoretical value is calculated based upon the PCIe generation and number of lanes. This value includes protocol overhead.

### Exporting and Querying Data

It is possible to access the metric values for automated processing using the Nsight Systems CLI export capabilities.

An example that extracts values of "SM Active":

          $ nsys export -t sqlite report.qdrep
          $ sqlite3 report.sqlite "SELECT rawTimestamp, CAST(JSON_EXTRACT(data, '$.\"SM Active\"') as INTEGER) as value FROM GENERIC_EVENTS WHERE value != 0 LIMIT 10"

          309277039|80
          309301295|99
          309325583|99
          309349776|99
          309373872|60
          309397872|19
          309421840|100
          309446000|100
          309470096|100
          309494161|99

An overview of the contents of the data stored in each event (JSON):

          $ sqlite3 report.sqlite "SELECT data FROM GENERIC_EVENTS LIMIT 1"
          {
          "Unallocated Warps in Active SM": "0",
          "Compute Warps In Flight": "52",
          "Pixel Warps In Flight": "0",
          "Vertex\/Tess\/Geometry Warps In Flight": "0",
          "Total SM Occupancy": "52",
          "GR Active (GE\/CE)": "100",
          "Sync Compute In Flight": "0",
          "Async Compute In Flight": "98",
          "NVLINK bytes received": "0",
          "NVLINK bytes transmitted": "0",
          "PCIe Rx Throughput": "0",
          "PCIe Tx Throughput": "1",
          "DRAM Read Throughput": "0",
          "DRAM Write Throughput": "0",
          "Tensor Active \/ FP16 Active": "0",
          "SM Issue": "10",
          "SM Active": "52"
          }

Values are integer percentages (0..100)

### Limitations

- If metrics sets with NVLink are used but the links are not active, they may appear as fully utilized.

- Only one tool that subscribes to these counters can be used at a time, therefore, Nsight Systems GPU metric sampling cannot be used at the same time as the following tools:

  - Nsight Graphics
  - Nsight Compute
  - DCGM (Data Center GPU Manager)

    Use the following command:

    - dcgmi profile --pause
    - dcgmi profile --resume

    Or API:

    - dcgmProfPause
    - dcgmProfResume
  - Non-NVIDIA products which use:
    - CUPTI sampling used directly in the application. CUPTI trace is okay (although it will block Nsight Systems CUDA trace)
    - DCGM library
- Nsight Systems limits the amount of memory that can be used to store GPU metrics sampling data. Analysis with higher sampling rates or on GPUs with more SMs has a risk of filling these buffers. This will lead to gaps with long samples on timeline. If you select that area on the timeline you will see that the counters will pause and remain at a steady state for a while. Future releases will reduce the frequency of this happening and better present these periods.

## 19. Network Communication Profiling

Nsight Systems can be used to profiles several popular network communication protocols. To enable this, please select the Communication profiling options dropdown.

Then select the libraries you would like to trace:

### 19.1. MPI API Trace

For Linux x86_64 and Power targets, Nsight Systems is capable of capturing information about the MPI APIs executed in the profiled process. It has built-in API trace support only for the OpenMPI and MPICH implementations of MPI and only for a default list of synchronous APIs.

If you require more control over the list of traced APIs or if you are using a different MPI implementation, see github nvtx pmpi wrappers. You can use this documentation to generate a shared object to wrap a list of synchronous MPI APIs with NVTX using the MPI profiling interface (PMPI). If you set your LD_PRELOAD environment variable to the path of that object, Nsight Systems will capture and report the MPI API trace information when NVTX tracing is enabled.

NVTX tracing is automatically enabled when MPI trace is turned on.

### 19.2. OpenSHMEM Library Trace

If OpenSHMEM library trace is selected Nsight Systems will trace the subset of OpenSHMEM API functions that are most likely be involved in performance bottlenecks. To keep overhead low Nsight Systems does not trace all functions.

OpenSHMEM 1.5 Functions Not Traced

    shmem_my_pe
    shmem_n_pes
    shmem_global_exit
    shmem_pe_accessible
    shmem_addr_accessible
    shmem_ctx_{create,destroy,get_team}
    shmem_global_exit
    shmem_info_get_{version,name}
    shmem_{my_pe,n_pes,pe_accessible,ptr}
    shmem_query_thread
    shmem_team_{create_ctx,destroy}
    shmem_team_get_config
    shmem_team_{my_pe,n_pes,translate_pe}
    shmem_team_split_{2d,strided}
    shmem_test*

### 19.3. UCX Library Trace

If UCX library trace is selected Nsight Systems will trace the subset of functions of the UCX protocol layer UCP that are most likely be involved in performance bottlenecks. To keep overhead low Nsight Systems does not trace all functions.

UCX functions traced:

    ucp_am_send_nb[x]
    ucp_am_recv_data_nbx
    ucp_am_data_release
    ucp_atomic_{add{32,64},cswap{32,64},fadd{32,64},swap{32,64}}
    ucp_atomic_{post,fetch_nb,op_nbx}
    ucp_cleanup
    ucp_config_{modify,read,release}
    ucp_disconnect_nb
    ucp_dt_{create_generic,destroy}
    ucp_ep_{create,destroy,modify_nb,close_nbx}
    ucp_ep_flush[{_nb,_nbx}]
    ucp_listener_{create,destroy,query,reject}
    ucp_mem_{advise,map,unmap,query}
    ucp_{put,get}[_nbi]
    ucp_{put,get}_nb[x]
    ucp_request_{alloc,cancel,check_status,is_completed}
    ucp_rkey_{buffer_release,destroy,pack,ptr}
    ucp_stream_data_release
    ucp_stream_recv_{data_nb,request_test}
    ucp_stream_{send,recv}_nb[x]
    ucp_stream_worker_poll
    ucp_tag_msg_recv_nb[x]
    ucp_tag_probe_nb
    ucp_tag_{send,recv}_nbr
    ucp_tag_{send,recv}_nb[x]
    ucp_tag_recv_request_test
    ucp_tag_send_sync_nb[x]
    ucp_worker_{create,destroy,get_address,get_efd,arm,fence,wait,signal,wait_mem}
    ucp_worker_flush[{_nb,_nbx}]
    ucp_worker_set_am_{handler,recv_handler}

UCX Functions Not Traced:

    ucp_config_print
    ucp_conn_request_query
    ucp_context_{query,print_info}
    ucp_get_version[_string]
    ucp_ep_{close_nb,print_info,rkey_unpack}
    ucp_mem_print_info
    ucp_request_{test,free,release}
    ucp_worker_{progress,query,release_address,print_info}

Additional API functions from other UCX layers may be added in a future version of the product.

### 19.4. NVIDIA NVSHMEM and NCCL Trace

The NVIDIA network communication libraries NVSHMEM and NCCL have been instrumented using NVTX annotations. To enable tracing these libraries in Nsight Systems, turn on NVTX tracing in the GUI or CLI. To enable the NVTX instrumentation of the NVSHMEM library, make sure that the environment variable `NVSHMEM_NVTX` is set properly, e.g. `NVSHMEM_NVTX=common`.

## 20. Debug Versions of ELF Files

Often, after a binary is built, especially if it is built with debug information (`-g` compiler flag), it gets stripped before deploying or installing. In this case, ELF sections that contain useful information, such as non-export function names or unwind information, can get stripped as well.

One solution is to deploy or install the original unstripped library instead of the stripped one, but in many cases this would be inconvenient. Nsight Systems can use missing information from alternative locations.

For target devices with Ubuntu, see Debug Symbol Packages. These packages typically install debug ELF files with `/usr/lib/debug` prefix. Nsight Systems can find debug libraries there, and if it matches the original library (e.g., the built-in `BuildID` is the same), it will be picked up and used to provide symbol names and unwind information.

Many packages have debug companions in the same repository and can be directly installed with APT (`apt-get`). Look for packages with the `-dbg` suffix. For other packages, refer to the Debug Symbol Packages wiki page on how to add the debs package repository. After setting up the repository and running apt-get update, look for packages with `-dbgsym` suffix.

To verify that a debug version of a library has been picked up and downloaded from the target device, look in the Module Summary section of Analysis Summary:

## 21. Reading Your Report in GUI

### 21.1. Generating a New Report

Users can generate a new report by stopping a profiling session. If a profiling session has been canceled, a report will not be generated, and all collected data will be discarded.

A new `.qdrep` file will be created and put into the same directory as the project file (`.qdproj`).

### 21.2. Opening an Existing Report

An existing `.qdrep` file can be opened using File > Open....

### 21.3. Sharing a Report File

Report files (`.qdrep`) are self-contained and can be shared with other users of Nsight Systems. The only requirement is that the same or newer version of Nsight Systems is always used to open report files.

Project files (`.qdproj`) are currently not shareable, since they contain full paths to the report files.

To quickly navigate to the directory containing the report file, right click on it in the Project Explorer, and choose Show in folder... in the context menu.

### 21.4. Report Tab

While generating a new report or loading an existing one, a new tab will be created. The most important parts of the report tab are:

- View selector — Allows switching between Analysis Summary, Timeline View, Diagnostics Summary, and Symbol Resolution Logs views.

- Timeline — This is where all charts are displayed.

- Function table — Located below the timeline, it displays statistical information about functions in the target application in multiple ways.

Additionally, the following controls are available:

- Zoom slider — Allows you to vertically zoom the charts on the timeline.

### 21.5. Analysis Summary View

This view shows a summary of the profiling session. In particular, it is useful to review the project configuration used to generate this report. Information from this view can be selected and copied using the mouse cursor.

### 21.6. Timeline View

The timeline view consists of two main controls: the timeline at the top, and a bottom pane that contains the events view and the function table. In some cases, when sampling of a process has not been enabled, the function table might be empty and hidden.

The bottom view selector sets the view that is displayed in the bottom pane.

### 21.6.1. Timeline

Timeline is a versatile control that contains a tree-like hierarchy on the left, and corresponding charts on the right.

Contents of the hierarchy depend on the project settings used to collect the report. For example, if a certain feature has not been enabled, corresponding rows will not be show on the timeline.

To display trace events in the Events View right-click a timeline row and select the “Show in Events View” command. The events of the selected row and all of its sub-rows will be displayed in the Events View.

If a timeline row has been selected for display in the Events View then double-clicking a timeline item on that row will automatically scroll the content of the Events View to make the corresponding Events View item visible and select it.

### Row Height

Several of the rows in the timeline use height as a way to model the percent utilization of resources. This gives the user insight into what is going on even when the timeline is zoomed all the way out.

In this picture you see that for kernel occupation there is a colored bar of variable height.

Nsight Systems calculates the average occupancy for the period of time represented by particular pixel width of screen. It then uses that average to set the top of the colored section. So, for instance, if 25% of that timeslice the kernel is active, the bar goes 25% of the distance to the top of the row.

In order to make the difference clear, if the percentage of the row height is non-zero, but would be represented by less than one vertical pixel, Nsight Systems displays it as one pixel high. The gray height represents the maximum usage in that time range.

This row height coding is used in the CPU utilization, thread and process occupancy, kernel occupancy, and memory transfer activity rows.

### 21.6.2. Events View

The Events View provides a tabular display of the trace events. The view contents can be searched and sorted.

Double-clicking an item in the Events View automatically focuses the Timeline View on the corresponding timeline item.

API calls, GPU executions, and debug markers that occurred within the boundaries of a debug marker are displayed nested to that debug marker. Multiple levels of nesting are supported.

Events view recognizes these types of debug markers:

- NVTX

- Vulkan VK_EXT_debug_marker markers, VK_EXT_debug_utils labels

- PIX events and markers

- OpenGL KHR_debug markers

### 21.6.3. Function Table Modes

The function table can work in three modes:

- Top-Down View — In this mode, expanding top-level functions provides information about the callee functions. One of the top-level functions is typically the main function of your application, or another entry point defined by the runtime libraries.

- Bottom-Up View — This is a reverse of the Top-Down view. On the top level, there are functions directly hit by the sampling profiler. To explore all possible call chains leading to these functions, you need to expand the subtrees of the top-level functions.

- Flat View — This view enumerates all functions ever observed by the profiler, even if they have never been directly hit, but just appeared somewhere on the call stack. This view typically provides a high-level overview of which parts of the code are CPU-intensive.

Each of the views helps understand particular performance issues of the application being profiled. For example:

- When trying to find specific bottleneck functions that can be optimized, the Bottom-Up view should be used. Typically, the top few functions should be examined. Expand them to understand in which contexts they are being used.

- To navigate the call tree of the application and while generally searching for algorithms and parts of the code that consume unexpectedly large amount of CPU time, the Top-Down view should be used.

- To quickly assess which parts of the application, or high level parts of an algorithm, consume significant amount of CPU time, use the Flat view.

The Top-Down and Bottom-Up views have Self and Total columns, while the Flat view has a Flat column. It is important to understand the meaning of each of the columns:

- Top-Down view

  - Self column denotes the relative amount of time spent executing instructions of this particular function.

  - Total column shows how much time has been spent executing this function, including all other functions called from this one. Total values of sibling rows sum up to the Total value of the parent row, or 100% for the top-level rows.

- Bottom-Up view

  - Self column for top-level rows, as in the Top-Down view, shows how much time has been spent directly in this function. Self times of all top-level rows add up to 100%.

  - Self column for children rows breaks down the value of the parent row based on the various call chains leading to that function. Self times of sibling rows add up to the value of the parent row.

- Flat view

  - Flat column shows how much time this function has been anywhere on the call stack. Values in this column do not add up or have other significant relationships.

  > Note: | If low-impact functions have been filtered out, values may not add up correctly to 100%, or to the value of the parent row. This filtering can be disabled.

  Contents of the symbols table is tightly related to the timeline. Users can apply and modify filters on the timeline, and they will affect which information is displayed in the symbols table:

- Per-thread filtering — Each thread that has sampling information associated with it has a checkbox next to it on the timeline. Only threads with selected checkboxes are represented in the symbols table.

- Time filtering — A time filter can be setup on the timeline by pressing the left mouse button, dragging over a region of interest on the timeline, and then choosing Filter by selection in the dropdown menu. In this case, only sampling information collected during the selected time range will be used to build the symbols table.

  Note: | If too little sampling data is being used to build the symbols table (for example, when the sampling rate is configured to be low, and a short period of time is used for time-based filtering), the numbers in the symbols table might not be representative or accurate in some cases.

### 21.6.4. Filter Dialog

- Collapse unresolved lines is useful if some of the binary code does not have symbols. In this case, subtrees that consist of only unresolved symbols get collapsed in the Top-Down view, since they provide very little useful information.
- Hide functions with CPU usage below X% is useful for large applications, where the sampling profiler hits lots of function just a few times. To filter out the "long tail," which is typically not important for CPU performance bottleneck analysis, this checkbox should be selected.

### 21.7. Diagnostics Summary View

This view shows important messages. Some of them were generated during the profiling session, while some were added while processing and analyzing data in the report. Messages can be one of the following types:

- Informational messages

- Warnings

- Errors

To draw attention to important diagnostics messages, a summary line is displayed on the timeline view in the top right corner:

Information from this view can be selected and copied using the mouse cursor.

### 21.8. Symbol Resolution Logs View

This view shows all messages related to the process of resolving symbols. It might be useful to debug issues when some of the symbol names in the symbols table of the timeline view are unresolved.

## 22. Adding Report to the Timeline

Starting with 2021.3, Nsight Systems can load multiple report files into a single timeline. This is a BETA feature and will be improved in the future releases. Please let us know about your experience on the forums or through Help > Send Feedback... in the main menu.

To load multiple report files into a single timeline, first start by opening a report as usual — using File > Open... from the main menu, or double clicking on a report in the Project Explorer window. Then additional report files can be loaded into the same timeline using one of the methods:

- File > Add Report (beta)... in the main menu, and select another report file that you want to open

- Right click on the report in the project explorer window, and click Add Report (beta)

### 22.1. Time Synchronization

When multiple reports are loaded into a single timeline, timestamps between them need to be adjusted, such that events that happened at the same time appear to be aligned.

Nsight Systems can automatically adjust timestamps based on UTC time recorded around the collection start time. This method is used by default when other more precise methods are not available. This time can be seen as `UTC time at t=0` in the Analysis Summary page of the report file. Refer to your OS documentation to learn how to sync the software clock using the Network Time Protocol (NTP). NTP-based time synchronization is not very precise, with the typical errors on the scale of one to tens of milliseconds.

Reports collected on the same physical machine can use synchronization based on Timestamp Counter (TSC) values. These are platform-specific counters, typically accessed in user space applications using the RDTSC instruction on x86_64 architecture, or by reading the CNTVCT register on Arm64. Their values converted to nanoseconds can be seen as `TSC value at t=0` in the Analysis Summary page of the report file. Reports synchronized using TSC values can be aligned with nanoseconds-level precision.

TSC-based time synchronization is activated automatically, when Nsight Systems detects that the same TSC value corresponds to very close UTC times. UTC time difference must be below 1 second in this case. This method is expected to only work for reports collected on the same physical machine.

To find out which synchronization method was used, navigate to the Analysis Summary tab of an added report and check the `Report alignment source` property of a target. Note, that the first report won’t have this parameter.

When loading multiple reports into a single timeline, it is always advisable to first check that time synchronization looks correct, by zooming into synchronization or communication events that are expected to be aligned.

### 22.2. Timeline Hierarchy

When reports are added to the same timeline Nsight Systems will automatically line them up by timestamps as described above. If you want Nsight Systems to also recognize matching process or hardware information, you will need to set environment variables `NSYS_SYSTEM_ID` and `NSYS_HW_ID` as shown below at the time of report collection (such as when using "nsys profile ..." command).

When loading a pair of given report files into the same timeline, they will be merged in one of the following configurations:

- Different hardware (default) — is used when reports are coming from different physical machines, and no hardware resources are shared in these reports. This mode is used by default, and can be additionally signalled by specifying different `NSYS_HW_ID` values.

- Different systems, same hardware — is used when reports are collected on different virtual machines (VMs) or containers on the same physical machine. To activate this mode, specify the same value of `NSYS_HW_ID` when collecting the reports.

- Same system — is used when reports are collected within the same operating system (or container) environment. In this mode a process identifier (PID) 100 will refer to the same process in both reports. To activate this mode, specify the same value of `NSYS_SYSTEM_ID` when collecting the reports.

The following diagrams demonstrate typical cases:

### 22.3. Example: MPI

A typical scenario is when a computing job is run using one of the MPI implementations. Each instance of the app can be profiled separately, resulting in multiple report files. For example:

    # Run MPI job without the profiler:
    mpirun <MPI-options> ./myApp
    # Run MPI job and profile each instance of the application:
    mpirun <MPI-options> nsys profile -o report-%p <nsys-options>./myApp

When each MPI rank runs on a different node, the command above works fine, since the default pairing mode (different hardware) will be used.

When all MPI ranks run the localhost only, use this command (value "A" was chosen arbitrarily, it can be any non-empty string):

`NSYS_SYSTEM_ID=A mpirun <MPI-options> nsys profile -o report-%p <nsys-options> ./myApp`

For convenience, the MPI rank can be encoded into the report filename. Specifics depend on the MPI implementation. For Open MPI, use the following command to create report files based on the global rank value:

`mpirun <MPI-options> nsys profile -o 'report-%q{OMPI_COMM_WORLD_RANK}' <nsys-options> ./myApp`

For MPICH, use the following command:

`mpirun <MPI-options> nsys profile -o 'report-%q{PMI_RANK}' <nsys-options> ./myApp`

### 22.4. Limitations

- Only report files collected with Nsight Systems version 2021.3 and newer are fully supported.

- Sequential reports collected in a single CLI profiling session cannot be loaded into a single timeline yet.

## 23. Using Nsight Systems Expert System

The Nsight Systems expert system is an emerging feature in Nsight Systems aimed at automatic detection of performance optimization opportunities in an application's profile. It uses a set of predefined rules to determine if the application has known bad patterns.

### Using Expert System from the CLI

usage:

    nsys [global-options] analyze [options]
           [qdrep-or-sqlite-file]

If a .qdrep file is given as the input file and there is no .sqlite file with the same name in the same directory, it will be generated.

Note: The Expert System view in the GUI will give you the equivalent command line.

### Using Expert System from the GUI

The Expert System View can be found in the same drop-down as the Events View. If there is no .sqlite file with the same name as the .qdrep file in the same directory, it will be generated.

The Expert System View has the following components:

1. Drop-down to select the rule to be run
2. Rule description and advice summary
3. CLI command that will give the same result
4. Table containing results of running the rule
5. Settings button that allows users to specify the rule’s arguments

A context menu is available to correlate the table entry with the timeline. The options are the same as the Events View:

- Highlight selected on timeline (double-click)
- Show current on timeline (ctrl+double-click)

The highlighting is not supported for rules that do not return an event but rather an arbitrary time range (e.g. GPU utilization rules).

The CLI and GUI share the same rule scripts and messages. There might be some formatting differences between the output table in GUI and CLI.

### Expert System Rules

Rules are scripts that run on the SQLite DB output from Nsight Systems to find common improvable usage patterns.

Each rule has an advice summary with explanation of the problem found and suggestions to address it. Only the top 50 results are displayed by default.

There are currently six CUDA rules in the expert system. They are described below. Additional rules will be made available in a future version of Nsight Systems.

### Synchronous Operation Rules

Asynchronous memcpy with pageable memory

This rule identifies asynchronous memory transfers that end up becoming synchronous if the memory is pageable. This rule is not applicable for Nsight Systems Embedded Platforms Edition

Suggestion: If applicable, use pinned memory instead

Synchronous Memcpy

This rule identifies synchronous memory transfers that block the host.

Suggestion: Use cudaMemcpy*Async APIs instead.

Synchronous Memset

This rule identifies synchronous memset operations that block the host.

Suggestion: Use cudaMemset*Async APIs instead.

Synchronization APIs

This rule identifies synchronization APIs that block the host until all issued CUDA calls are complete.

Suggestions: Avoid excessive use of synchronization. Use asynchronous CUDA event calls, such as cudaStreamWaitEvent and cudaEventSynchronize, to prevent host synchronization.

### GPU Low Utilization Rules

GPU Starvation

This rule identifies time ranges where a GPU is idle for longer than 500ms. The threshold is adjustable.

Suggestions: Use CPU sampling data, OS Runtime blocked state backtraces, and/or OS Runtime APIs related to thread synchronization to understand if a sluggish or blocked CPU is causing the gaps. Add NVTX annotations to CPU code to understand the reason behind the gaps.

Notes:

- For each process, each GPU is examined, and gaps are found within the time range that starts with the beginning of the first GPU operation on that device and ends with the end of the last GPU operation on that device.
- GPU gaps that cannot be addressed by the user are excluded. This includes:
  - CUDA profiling overhead in the middle of a GPU gap.
  - The initial gap in the report that is seen before the first GPU operation.
  - The final gap that is seen after the last GPU operation.

GPU Low Utilization

This rule identifies time regions with low utilization.

Suggestions: Use CPU sampling data, OS Runtime blocked state backtraces, and/or OS Runtime APIs related to thread synchronization to understand if a sluggish or blocked CPU is causing the gaps. Add NVTX annotations to CPU code to understand the reason behind the gaps.

Notes:

- For each process, each GPU is examined, and gaps are found within the time range that starts with the beginning of the first GPU operation on that device and ends with the end of the last GPU operation on that device. This time range is then divided into equal chunks, and the GPU utilization is calculated for each chunk. The utilization includes all GPU operations as well as CUDA profiling overheads that the user cannot address.
- The utilization refers to the "time" utilization and not the "resource" utilization. This rule attempts to find time gaps when the GPU is or isn't being used, but does not take into account how many GPU resources are being used. Therefore, a single running memcpy is considered the same amount of "utilization" as a huge kernel that takes over all the cores. If multiple operations run concurrently in the same chunk, their utilization will be added up and may exceed 100%.
- Chunks with an in-use percentage less than the threshold value are displayed. If consecutive chunks have a low in-use percentage, the individual chunks are coalesced into a single display record, keeping the weighted average of percentages. This is why returned chunks may have different durations.

## 24. Broken Backtraces on Tegra

In Nsight Systems Embedded Platforms Edition, in the symbols table there is a special entry called Broken backtraces. This entry is used to denote the point in the call chain where the unwinding algorithms used by Nsight Systems could not determine what is the next (caller) function.

Broken backtraces happen because there is no information related to the current function that the unwinding algorithms can use. In the Top-Down view, these functions are immediate children of the Broken backtraces row.

One can eliminate broken backtraces by modifying the build system to provide at least one kind of unwind information. The types of unwind information, used by the algorithms in Nsight Systems, include the following:

For ARMv7 binaries:

- DWARF information in ELF sections: `.debug_frame`, `.zdebug_frame`, `.eh_frame`, `.eh_frame_hdr`. This information is the most precise. `.zdebug_frame` is a compressed version of `.debug_frame`, so at most one of them is typically present. `.eh_frame_hdr` is a companion section for `.eh_frame` and might be absent.

  Compiler flag: `-g`.

- Exception handling information in EHABI format provided in `.ARM.exidx` and `.ARM.extab` ELF sections. `.ARM.extab` might be absent if all information is compact enough to be encoded into `.ARM.exidx`.

  Compiler flag: `-funwind-tables`.

- Frame pointers (built into the `.text` section).

  Compiler flag: `-fno-omit-frame-pointer`.

For Aarch64 binaries:

- DWARF information in ELF sections: `.debug_frame`, `.zdebug_frame`, `.eh_frame`, `.eh_frame_hdr`. See additional comments above.

  Compiler flag: `-g`.

- Frame pointers (built into the `.text` section).

  Compiler flag: `-fno-omit-frame-pointer`.

The following ELF sections should be considered empty if they have size of 4 bytes: `.debug_frame`, `.eh_frame`, `.ARM.exidx`. In this case, these sections only contain termination records and no useful information.

For GCC, use the following compiler invocation to see which compiler flags are enabled in your toolchain by default (for example, to check if `-funwind-tables` is enabled by default):

    $ gcc -Q --help=common

For GCC and Clang, add `-###` to the compiler invocation command to see which compiler flags are actually being used.

Since EHABI and DWARF information is compiled on per-unit basis (every `.cpp` or `.c` file, as well as every static library, can be built with or without this information), presence of the ELF sections does not guarantee that every function has necessary unwind information.

Frame pointers are required by the Aarch64 Procedure Call Standard. Adding frame pointers slows down execution time, but in most cases the difference is negligible.

## 25. Launch Processes in Stopped State

In many cases, it is important to profile an application from the very beginning of its execution. When launching processes, Nsight Systems takes care of it by making sure that the profiling session is fully initialized before making the `exec()` system call on Linux, and by using the JDWP protocol on Android.

If the process launch capabilities of Nsight Systems are not sufficient, the application should be launched manually, and the profiler should be configured to attach to the already launched process. One approach would be to call `sleep()` somewhere early in the application code, which would provide time for the user to attach to the process in Nsight Systems Embedded Platforms Edition, but there are two other more convenient mechanisms that can be used on Linux, without the need to recompile the application. (Note that the rest of this section is only applicable to Linux-based target devices, not Windows or Android.)

Both mechanisms ensure that between the time the process is created (and therefore its PID is known) and the time any of the application's code is called, the process is stopped and waits for a signal to be delivered before continuing.

### 25.1. LD_PRELOAD

The first mechanism uses `LD_PRELOAD` environment variable. It only works with dynamically linked binaries, since static binaries do not invoke the runtime linker, and therefore are not affected by the `LD_PRELOAD` environment variable.

- For ARMv7 binaries, preload

      /opt/nvidia/nsight_systems/libLauncher32.so

- Otherwise if running from host, preload

      /opt/nvidia/nsight_systems/libLauncher64.so

- Otherwise if running from CLI, preload

      [installation_directory]/libLauncher64.so

The most common way to do that is to specify the environment variable as part of the process launch command, for example:

    $ LD_PRELOAD=/opt/nvidia/nsight_systems/libLauncher64.so ./my-aarch64-binary --arguments

When loaded, this library will send itself a `SIGSTOP` signal, which is equivalent to typing `Ctrl+Z` in the terminal. The process is now a background job, and you can use standard commands like jobs, `fg` and `bg` to control them. Use `jobs -l` to see the PID of the launched process.

When attaching to a stopped process, Nsight Systems will send `SIGCONT` signal, which is equivalent to using the `bg` command.

### 25.2. Launcher

The second mechanism can be used with any binary. Use `[installation_directory]/launcher` to launch your application, for example:

    $ /opt/nvidia/nsight_systems/launcher ./my-binary --arguments

The process will be launched, daemonized, and wait for `SIGUSR1` signal. After attaching to the process with Nsight Systems, the user needs to manually resume execution of the process from command line:

    $ pkill -USR1 launcher

Note: | Note that `pkill` will send the signal to any process with the matching name. If that is not desirable, use `kill` to send it to a specific process. The standard output and error streams are redirected to `/tmp/stdout_<PID>.txt` and `/tmp/stderr_<PID>.txt`.

The launcher mechanism is more complex and less automated than the LD_PRELOAD option, but gives more control to the user.

## 26. Import NVTXT

ImportNvtxt is an utility which allows conversion of a NVTXT file to a Nsight Systems report file (*.qdrep) or to merge it with an existing report file.

Note: NvtxtImport supports custom TimeBase values. Only these values are supported:

- Manual — timestamps are set using absolute values.

- Relative — timestamps are set using relative values with regards to report file which is being merged with nvtxt file.

- ClockMonotonicRaw — timestamps values in nvtxt file are considered to be gathered on the same target as the report file which is to be merged with nvtxt using `clock_gettime(CLOCK_MONOTONIC_RAW, ...)` call.

- CNTVCT — timestamps values in nvtxt file are considered to be gathered on the same target as the report file which is to be merged with nvtxt using CNTVCT values.

You can get usage info via help message:

Print help message:

    -h [ --help ]

Show information about report file:

    --cmd info -i [--input] arg

Create report file from existing nvtxt file:

    --cmd create -n [--nvtxt] arg -o [--output] arg [-m [--mode] mode_name mode_args] [--target <Hw:Vm>] [--update_report_time]

Merge nvtxt file to existing report file:

    --cmd merge -i [--input] arg -n [--nvtxt] arg -o [--output] arg [-m [--mode] mode_name mode_args] [--target <Hw:Vm>] [--update_report_time]

Modes description:

- lerp - Insert with linear interpolation

      --mode lerp --ns_a arg --ns_b arg [--nvtxt_a arg --nvtxt_b arg]

- lin - insert with linear equation

      --mode lin  --ns_a arg --freq arg [--nvtxt_a arg]

Modes' parameters:

- ns_a - a nanoseconds value

- ns_b - a nanoseconds value (greater than ns_a)

- nvtxt_a - an nvtxt file's time unit value corresponding to ns_a nanoseconds

- nvtxt_b - an nvtxt file's time unit value corresponding to ns_b nanoseconds

- freq - the nvtxt file's timer frequency

- --target <Hw:Vm> - specify target id, e.g. --target 0:1

- --update_report_time - prolong report's profiling session time while merging if needed. Without this option all events outside the profiling session time window will be skipped during merging.

### Commands

Info

To find out report's start and end time use info command.

Usage:

    ImportNvtxt --cmd info -i [--input] arg

Example:

    ImportNvtxt info Report.qdrep
    Analysis start (ns)	83501026500000
    Analysis end (ns)	83506375000000

Create

You can create a report file using existing NVTXT with create command.

Usage:

    ImportNvtxt --cmd create -n [--nvtxt] arg -o [--output] arg [-m [--mode] mode_name mode_args]

Available modes are:

- lerp — insert with linear interpolation.

- lin — insert with linear equation.

Usage for lerp mode is:

    --mode lerp --ns_a arg --ns_b arg [--nvtxt_a arg --nvtxt_b arg]

with:

- `ns_a` — a nanoseconds value.

- `ns_b` — a nanoseconds value (greater than `ns_a`).

- `nvtxt_a` — an nvtxt file's time unit value corresponding to `ns_a` nanoseconds.

- `nvtxt_b` — an nvtxt file's time unit value corresponding to `ns_b` nanoseconds.

If `nvtxt_a` and `nvtxt_b` are not specified, they are repectively set to nvtxt file's minimum and maximum time value.

Usage for lin mode is:

    --mode lin --ns_a arg --freq arg [--nvtxt_a arg]

with:

- `ns_a` — a nanoseconds value.

- `freq` — the nvtxt file's timer frequency.

- `nvtxt_a` — an nvtxt file's time unit value corresponding to `ns_a` nanoseconds.

If `nvtxt_a` is not specified, it is set to nvtxt file's minimum time value.

Examples:

    ImportNvtxt --cmd create -n Sample.nvtxt -o Report.qdrep

The output will be a new generated report file which can be opened and viewed by Nsight Systems.

Merge

To merge NVTXT file with an existing report file use merge command.

Usage:

    ImportNvtxt --cmd merge -i [--input] arg -n [--nvtxt] arg -o [--output] arg [-m [--mode] mode_name mode_args]

Available modes are:

- lerp — insert with linear interpolation.

- lin — insert with linear equation.

Usage for lerp mode is:

    --mode lerp --ns_a arg --ns_b arg [--nvtxt_a arg --nvtxt_b arg]

with:

- `ns_a` — a nanoseconds value.

- `ns_b` — a nanoseconds value (greater than `ns_a`).

- `nvtxt_a` — an nvtxt file's time unit value corresponding to `ns_a` nanoseconds.

- `nvtxt_b` — an nvtxt file's time unit value corresponding to `ns_b` nanoseconds.

If `nvtxt_a` and `nvtxt_b` are not specified, they are repectively set to nvtxt file's minimum and maximum time value.

Usage for lin mode is:

    --mode lin  --ns_a arg --freq arg [--nvtxt_a arg]

with:

- `ns_a` — a nanoseconds value.

- `freq` — the nvtxt file's timer frequency.

- `nvtxt_a` — an nvtxt file's time unit value corresponding to `ns_a` nanoseconds.

If `nvtxt_a` is not specified, it is set to nvtxt file's minimum time value.

Time values in `<filename.nvtxt>` are assumed to be nanoseconds if no mode specified.

Example

    ImportNvtxt --cmd merge -i Report.qdrep -n Sample.nvtxt -o NewReport.qdrep

## Visual Studio Integration

NVIDIA Nsight Integration is a Visual Studio extension that allows you to access the power of Nsight Systems from within Visual Studio.

When Nsight Systems is installed along with NVIDIA Nsight Integration, Nsight Systems activities will appear under the NVIDIA Nsight menu in the Visual Studio menu bar. These activities launch Nsight Systems with the current project settings and executable.

Selecting the "Trace" command will launch Nsight Systems, create a new Nsight Systems project and apply settings from the current Visual Studio project:

- Target application path

- Command line parameters

- Working folder

If the "Trace" command has already been used with this Visual Studio project then Nsight Systems will load the respective Nsight Systems project and any previously captured trace sessions will be available for review using the Nsight Systems project explorer tree.

For more information about using Nsight Systems from within Visual Studio, please visit

- NVIDIA Nsight Integration Overview

- NVIDIA Nsight Integration User Guide

## 28. Troubleshooting

If the profiler behaves unexpectedly during the profiling session, or the profiling session fails to start, try the following steps:

- Close the host application.
- Restart the target device.
- Start the host application and connect to the target device.

To enable logging on the host, refer to this config file:

    host-linux-x64/nvlog.config.template

When reporting any bugs please include the build version number as described in the Help → About dialog. If possible, attach log files and report (`.qdrep`) files, as they already contain necessary version information.

Nsight Systems uses a settings file (`NVIDIA Nsight Systems.ini`) on the host to store information about loaded projects, report files, window layout configuration, etc. Location of the settings file is described in the Help → About dialog. Deleting the settings file will restore Nsight Systems to a fresh state, but all projects and reports will disappear from the Project Explorer.

### GUI Troubleshooting

If opening the Nsight Systems Linux GUI fails with the following error, you may be missing some required libraries:

    This application failed to start because it could not find or load the Qt platform plugin "xcb" in "". Available platform plugins are: xcb. Reinstalling the application may fix this problem.

Launch Nsight Systems using the following command line to determine which libraries are missing and install them.

    $ QT_DEBUG_PLUGINS=1 ./nsys-ui

If the workload does not run when launched via Nsight Systems or the timeline is empty, check the stderr.log and stdout.log (click on drop-down menu showing Timeline View and click on Files) to see the errors encountered by the app.

### Android Targets

When connecting to an Android-based device, Nsight Systems installs its executable and library files into the following directory:

    /data/local/tmp/com.nvidia.nsightsystems.tools/

Logs on the target device are collected into this file:

    /data/local/tmp/com.nvidia.nsightsystems.tools/nsys.log

To enable verbose logging on the target device, follow these steps:

1. Close the host application.

2. Place nvlog.config from host directory to `/sdcard/` directory on target.

3. Restart the target device.

4. From ADB shell, launch the following command:

       /data/local/tmp/com.nvidia.nsightsystems.tools/nsys --daemon --debug

   On rooted Android devices, the command above should be started from superuser (e.g., `adb shell su -c ...`).

5. Start the host application and connect to the target device.

Please note that in some cases, debug logging can significantly slow down the profiler

### Symbol Resolution

If stack trace information is missing symbols and you have a symbol file, you can manually re-resolve using the ResolveSymbols utility. This can be done by right-clicking the report file in the Project Explorer window and selecting "Resolve Symbols...".

Alternatively, you can find the utility as a separate executable in the `[installation_path]\Host` directory. This utility works with ELF format files, with Windows PDB directories and symbol servers, or with files where each line is in the format `<start><length><name>`.

Short | Long | Argument | Description
--- | --- | --- | ---
-h | --help |  | Help message providing information about available options.
-l | --process-list |  | Print global process IDs list
-s | --sym-file | filename | Path to symbol file
-b | --base-addr | address | If set then <start> in symbol file is treated as relative address starting from this base address
-p | --global-pid | pid | Which process in the report should be resolved. May be omitted if there is only one process in the report.
-f | --force |  | This option forces use of a given symbol file.
-i | --report | filename | Path to the report with unresolved symbols.
-o | --output | filename | Path and name of the output file. If it is omitted then "resolved" suffix is added to the original filename.
-d | --directories | directory paths | List of symbol folder paths, separated by semi-colon characters. Available only on Windows.
-v | --servers | server URLs | List of symbol servers that uses the same format as `_NT_SYMBOL_PATH` environment variable, i.e. `srv*<LocalStore>*<SymbolServerURL>`. Available only on Windows.
-n | --ignore-nt-sym-path |  | Ignore the symbol locations stored in the `_NT_SYMBOL_PATH` environment variable. Available only on Windows.

### Verbose Logging on Linux Targets

Verbose logging is available when connecting to a Linux-based device from the GUI on the host. This extra debug information is not available when launching via the command line. Nsight Systems installs its executable and library files into the following directory:

    /opt/nvidia/nsight_systems/

To enable verbose logging on the target device, when launched from the host, follow these steps:

1. Close the host application.

2. Restart the target device.

3. Place `nvlog.config` from host directory to the `/opt/nvidia/nsight_systems` directory on target.

4. From SSH console, launch the following command:

       sudo /opt/nvidia/nsight_systems/nsys --daemon --debug

5. Start the host application and connect to the target device.

Logs on the target devices are collected into this file (if enabled):

    nsys.log

in the directory where `nsys` command was launched.

Please note that in some cases, debug logging can significantly slow down the profiler.

### Verbose Logging on Windows Targets

Verbose logging is available when connecting to a Windows-based device from the GUI on the host. Nsight Systems installs its executable and library files into the following directory by default:

    C:\Program Files\NVIDIA Corporation\Nsight Systems 2021.3

To enable verbose logging on the target device, when launched from the host, follow these steps:

1. Close the host application.

2. Terminate the `nsys` process.

3. Place `nvlog.config` from host directory next to Nsight Systems Windows agent on the target device

   - Local Windows target:

         C:\Program Files\NVIDIA Corporation\Nsight Systems 2021.3\target-windows-x64

   - Remote Windows target:

         C:\Users\<user name>\AppData\Local\Temp\nvidia\nsight_systems

4. Start the host application and connect to the target device.

Logs on the target devices are collected into this file (if enabled):

    nsight-sys.log

in the same directory as Nsight Systems Windows agent.

Please note that in some cases debug logging can significantly slow down the profiler.

### QNX Troubleshooting

Common issues with QNX targets:

- Make sure that `tracelogger` utility is available and can be run on the target.

- Make sure that `/tmp` directory is accessible and supports sub-directories.

- When switching between Nsight Systems versions, processes related to the previous version, including profiled applications forked by the daemon, must be killed before the new version is used. If you experience issues after switching between Nsight Systems versions, try rebooting the target.

## Other Resources

Looking for information to help you use Nsight Systems the most effectively? Here are some more resources you might want to review:

### Feature Videos

Short videos, only a minute or two, to introduce new features.

- OpenMP Trace Feature Spotlight
- Command Line Sessions Video Spotlight
- Direct3D11 Feature Spotlight
- Vulkan Trace
- Statistics Driven Profiling

### Blog Posts

NVIDIA developer blogs, these are longer form, technical pieces written by tool and domain experts.

- 2019 - Migrating to NVIDIA Nsight Tools from NVVP and nvprof
- 2019 - Transitioning to Nsight Systems from NVIDIA Visual Profiler / nvprof
- 2019 - NVIDIA Nsight Systems Add Vulkan Support
- 2019 - TensorFlow Performance Logging Plugin nvtx-plugins-tf Goes Public
- 2020 - NVIDIA Nsight Systems in Containers and the Cloud
- 2020 - Understanding the Visualization of Overhead and Latency in Nsight Systems

### Training Seminars

2018 NCSA Blue Waters Webinar - Introduction to NVIDIA Nsight Systems

### Conference Presentations

- GTC 2020 - Rebalancing the Load: Profile-Guided Optimization of the NAMD Molecular Dynamics Program for Modern GPUs using Nsight Systems
- GTC 2020 - Scaling the Transformer Model Implementation in PyTorch Across Multiple Nodes
- GTC 2019 - Using Nsight Tools to Optimize the NAMD Molecular Dynamics Simulation Program
- GTC 2019 - Optimizing Facebook AI Workloads for NVIDIA GPUs
- GTC 2018 - Optimizing HPC Simulation and Visualization Codes Using NVIDIA Nsight Systems
- GTC 2018 - Israel - Boost DNN Training Performance using NVIDIA Tools
- Siggraph 2018 - Taming the Beast; Using NVIDIA Tools to Unlock Hidden GPU Performance

### For More Support

To file a bug report or to ask a question on the Nsight Systems forums, you will need to register with the NVIDIA Developer Program. See the FAQ. You do not need to register to read the forums.

After that, you can access Nsight Systems Forums and the NVIDIA Bug Tracking System.

To submit feedback directly from the GUI, go to Help->Send Feedback and fill out the form. Enter your email address if you would like to hear back from the Nsight Systems team.