How to Run a Perfetto Trace on Oculus Quest or Quest 2

Emitting Data from your App

Perfetto Setup

1. Create a working directory that will contain the Perfetto configuration, scripts, and trace output
• For the purposes of this post, we'll call the directory perfetto_traces, but you can name it whatever you want.
2. Create your Perfetto configuration (config.txt)
• Create a text file at perfetto_traces/config.txt.
• Populate the file with your trace configuration. The best starting place is to use the Web UI (https://ui.perfetto.dev/⁠) to generate a Perfetto configuration, and then tweak it from there.
• In the Web UI, click Record new trace.
• Select the various data sources you'd like to record.
• Copy the config presented in the Trace command section. Make sure to only copy the configuration, not the entire command (see selected text).

NOTE: Both Perfetto app instrumentation and VrApi/GPU metrics are part of Perfetto TrackEvents, which is a data source the Web UI does not support generating configurations for. In order to record these, add the following to your config:
data_sources: {
    config {
        name: "track_event"
    }
}

NOTE: GPU metrics require that adb shell ovrgpuprofiler -r is running in the background for the duration of the trace.
Example Config File
Below is an example config file that will record VrApi and GPU metrics, as well as any other Perfetto TrackEvents being emitted on the device.
buffers: {
    size_kb: 63488
    fill_policy: DISCARD
}
buffers: {
    size_kb: 2048
    fill_policy: DISCARD
}
data_sources: {
    config {
        name: "linux.process_stats"
        target_buffer: 1
        process_stats_config {
             scan_all_processes_on_start: true
         }
     }
}
data_sources: {
    config: {
       name: "track_event"
     }
}
duration_ms: 10000


3. Create the Python script to record the trace (perfetto.py).
• Create a text file at perfetto_traces/perfetto.py.
• Paste the following into the file:
#!/usr/bin/env python3

import os
import subprocess
import sys

dir = os.path.dirname(os.path.realpath(__file__))
config_file = os.path.join(dir, "config.txt")
output_file = os.path.join(dir, "trace.pftrace")

if not os.path.isfile(config_file):
    print("Config file does not exist: " + config_file)
    sys.exit(1)
config = open(config_file, 'r')

subprocess.run(["adb", "shell", "rm", "-f", "/data/misc/perfetto-traces/trace"], check=False)
subprocess.run(["adb", "shell", "perfetto", "-c", "-", "--txt", "-o",
"/data/misc/perfetto-traces/trace"], stdin=config, check=True)
if os.path.isfile(output_file):
    os.remove(output_file)
subprocess.run(["adb", "pull", "/data/misc/perfetto-traces/trace", output_file], check=True)

4. (Optional) Create a Custom Command in Oculus Developer Hub (ODH) to run the script.
• Make sure your Quest is connected to ODH.
• Under the My Device tab, click + Create Command.
• Name: Perfetto
• Command: python3 <absolute path>/perfetto_traces/perfetto.py
• Display command output in a new window: Checked
• For more information on ODH Customer Commands, click here.

Recording and Viewing Traces

• Make sure your Quest is connected to your PC.
• Check that your Quest is listed when you run the command adb devices.
• Open your app and get into the scenario you want to profile.
• Run perfetto.py using Python3 - This will copy your config to the device, run Perfetto, and copy the recorded trace back to the directory.
• Alternatively, if using ODH, run the Perfetto Custom Command in ODH
• Your recorded trace will be saved to perfetto_traces/trace.pftrace.

• Open the Web UI: https://ui.perfetto.dev/⁠
• Click `Open trace file` and select the trace you just recorded, located at perfetto_traces/trace.pftrace.

Git Bash / WSL / Cygwin Script

• Create a text file at perfetto_traces/perfetto.sh.
• Paste the following into the file: