Project Dory: Difference between revisions

Revision as of 04:09, 29 November 2017

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.

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?

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.

Preference Name	Gist URL
network.buffer.cache.size	https://gist.github.com/0ffacfb61ce17a730df6cb2f18fa1483
network.http.spdy.chunk-size	https://gist.github.com/0ef99bb241f8de7392b592c34a605b3b
javascript.options.baselinejit.threshold	https://gist.github.com/6b2ffc3dfcdab7872c11116c79a7ad0e
javascript.options.ion.threshold	https://gist.github.com/ddf16cb123c5296cf3ca4a69a2ba6cf8
network.predictor.preconnect-min-confidence	https://gist.github.com/72dae79449b55d14e1e3a5dc67121a7f
layout.display-list.retain	https://gist.github.com/cfafaa3b88f3e0ce55dc091e3ac5190d
network.tcp.sendbuffer	https://gist.github.com/c89ed6ea370df9b67371966ff5c52a41
network.http.speculative-parallel-limit	https://gist.github.com/18f72b4c30ec552cdb7cf17cce8febaa
layers.tile-width	https://gist.github.com/6e283306aad2113c8196b5d57201ba18
network.http.spdy.default-concurrent	https://gist.github.com/4118e79b7a7ce3982747912913323130
dom.idle_period.throttled_length	https://gist.github.com/f2d0285587888c42a36bdecda967c4ee
layers.tile-height	https://gist.github.com/4e82e980238c740e4e9dd41e729c0e9f
network.http.max-persistent-connections-per-server	https://gist.github.com/8994e522a9eb6dc4f7fe1c79320bd215
network.buffer.cache.count	https://gist.github.com/7c8b2ca0d987f0ed6897695c35a55095

Test result summary
- javascript.options.baselinejit.threshold: for most test cases that completes quickly (< 100 ms), the default value performs similarly to the other values. Setting it to 50 is likely to have a smaller variation. For test cases that take longer time (> 200 ms) Setting the pref to 50 almost outperforms the default value. The only exception is test 'test_firefox_gslide_ail_pagedown_0', but the difference is marginal (within 1 frame).
- javascript.options.ion.threshold: for test cases that completes under 100 ms, the default value (1000) or a larger value almost always perform better than 1. For some test cases (< 100 ms), the default value performs worse than 1, but the difference is marginal: test 'test_firefox_gsearch_ail_select_search_suggestion' completes in 15 ms in average using threshold 1, which is about 1 frame faster than the default. For larger test cases that completes > 300 ms, the default is almost always better than 1, showing that the performance gain is offset by the cost of compilation, and 10000 performs slightly better than the default for gmail and Facebook. One test that is of interest is 'test_firefox_outlook_ail_composemail_0', in which using 1 for eager compilation performs significantly better then default (about 100ms in difference). This is worthy of further look.

@@ Line 77: / Line 77: @@
 * Test result summary
 ** javascript.options.baselinejit.threshold: for most test cases that completes quickly (< 100 ms), the default value performs similarly to the other values. Setting it to 50 is likely to have a smaller variation. For test cases that take longer time (> 200 ms) Setting the pref to 50 almost outperforms the default value. The only exception is test 'test_firefox_gslide_ail_pagedown_0', but the difference is marginal (within 1 frame).
+** javascript.options.ion.threshold: for test cases that completes under 100 ms, the default value (1000) or a larger value almost always perform better than 1. For some test cases (< 100 ms), the default value performs worse than 1, but the difference is marginal: test 'test_firefox_gsearch_ail_select_search_suggestion' completes in 15 ms in average using threshold 1, which is about 1 frame faster than the default. For larger test cases that completes > 300 ms, the default is almost always better than 1, showing that the performance gain is offset by the cost of compilation, and 10000 performs slightly better than the default for gmail and Facebook. One test that is of interest is 'test_firefox_outlook_ail_composemail_0', in which using 1 for eager compilation performs significantly better then default (about 100ms in difference). This is worthy of further look.
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