chromium-profiler

Chromium-profiler is a utility to test some web page cases in Chromium, meant to profile Chromium for PGO.

Why?

• Current versions of Google Chrome are compiled with PGO (Profile Guided Optimizations). We also want this for Chromium.

• Chromium source code contains documentation for how to compile with PGO, but

  1. The tools/perf/run_benchmark utility used for profiling depends on vpython and various other stuff (most of that is bundled in Chromium sources, but not all).
  2. The profiling cases for the tools/perf/run_benchmark need Web Page Replay archives, which Google does not share publicly.

  For automatized profiling the community therefore needs to create it's own Web Page Replay archives.

Dependencies

• Web Page Replay compiled as a binary with name wpr (Gentoo package dev-util/web_page_replay_go from this repository)
• Selenium WebDriver (Gentoo package dev-python/selenium)

How to use

To run all test cases, run

./chromium_profiler.py --chrome-executable PATH_TO_CHROME --chromedriver-executable PATH_TO_CHROMEDRIVER

replacing PATH_TO_CHROME and PATH_TO_CHROMEDRIVER as needed. On amd64 Gentoo, for example, these are /usr/lib64/chromium-browser/chrome and /usr/lib64/chromium-browser/chromedriver.

If Chromium is compiled to generate LLVM profiling data, the results will be stored in various files in a temporary directory and removed after the run. If the --profile-output option is specified, the profiling results of all the runs will be incrementally merged with the llvm-profdata utility into the file specified by that option. Thus the llvm-profdata utility must be in the PATH environment variable if --profile-output option is specified.

To list available cases, use the --list-cases option.

To test specific cases, use the --case option, which accepts glob-style patterns and can be used multiple times.

To use additional arguments for starting the browser, use the --add-arg option.