Project Dory

Project Goals

• Investigate the usage of current preferences:
  • Understand and document existing preferences (lifetime, type, whether they are still in use, etc.)
  • Clean up preferences (unused, incorrectly used, non-obvious).
• Use preferences as performance tuning knobs and investigate the performance implications of these knobs.
  • Prioritize the preferences with their relevance to performance.
  • Tweak the preferences and run automated tests against the values to see their performance implications.

Participants

• Kan-Ru Chen
• Cervantes Yu
• Will Wang
• WeiCheng Pan
• Shako Ho
• Walter Chen
• Askeing Yen

Roadmap

• Find a systematic way to manage and prioritize default preference values.
  • Co-work with libpref redesign project on new persistence format of preferences.
  • Find performance related preferences during the process.
  • Get feedback from relevant teams.
    • Initially we may target JS related preferences.
  • Record the performance implications of preferences using the new persistence format.

Things to Consider

• What's the new persistence format for preferences?
• What data should a pref contain?
  • Internal name, a more descriptive name, description, default value, etc.
• #include from smaller subsets in the final pref file.
  • Group prefs that are relevant (sharing the same prefix) in smaller files.
• Standalone top branch indicates that the pref should be under some other branch.
  • There is only 1 pref beginning with "slider": slider.snapMultiplier
  • Move to browser.slider.snapMultiplier?
• camelCase, underscore_names, or dashed-names?
• Envisioning a front-end user interface that is more user-friendly than about:config?
  • Makes it easier for users to tweak or experiment with the browser.
• Inline readonly prefs in code as constants?

Results

• A Hasal trial run to test the performance effect of changing JS baseline JIT threshold values:
  • https://gist.github.com/ShakoHo/2e2321294d567d913eea5eaa58af60e0
  • Twiddling the preference has influence of performance as can be seen in the test results, but there is no consistent change among the tests.