# Gpuvis Tracing Annotations

Gpuvis is a tool to visualize ftrace traces, with support for most GPU drivers to show GPU activity.

Mesa can emit trace markers to be displayed in Gpuvis, which is useful for figuring out why e.g. stalls are happening.

## Run on Linux

Any traces can be made with trace-cmd. The Gpuvis repository contains scripts for configuring the markers needed for GPU events. To start tracing:

    sh trace-cmd-setup.sh && sh trace-cmd-start-tracing.sh
    # Start your game etc. Then to capture a trace
    sh trace-cmd-capture.sh
    # and to finally stop
    sh trace-cmd-stop-tracing.sh

The resulting trace file can be opened with Gpuvis.

## Run on SteamOS

SteamOS includes a script (gpu-trace) to capture traces.

    sudo gpu-trace
    # Press Ctrl+C to stop capture and open report in gpuvis

Note that on SteamOS gpuvis is actually not installed by default, but the script does write a gpu-trace.zip file in the current working directory. To open it you’ll want to do the following on your development machine:

    scp sd-host:gpu-trace.zip ./
    unzip gpu-trace.zip
    ./trace-cmd convert -i *.dat -o converted.dat --compression none --file-version 6
    gpuvis *.json converted.dat

The main advantage of the gpu-trace script is that it has an integration with perf, so Gpuvis can also visualize perf samples in the timeline. Note that the perf file is preprocessed before being put into the zip file, so the trace is portable between machines.

## Annotations in Steam games

Steam games are run in a container, and need the environment variable PRESSURE_VESSEL_DEVEL=1 to set up the tracing filesystem so the trace marker can be written. This can e.g. be done by going to the game properties in Steam and setting the command line to

    PRESSURE_VESSEL_DEVEL=1 %command%

Then you can run the game as usual, and the driver will write trace annotations.