[LayoutNG] cs.chromium.org is painfully slow |
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Issue descriptionThis is the only page I use daily but often prefer not to dogfood because it's too slow atm, filing to share information and track progress. Example URL: https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/layout/layout_object.h It looks like we spent most of our time in: LayoutFlexibleBox::UpdateBlockLayout LayoutFlexibleBox::LayoutFlexItems ... HandleInFlow Not sure if we call HandleInFlow too many times, or some parts of HandleInFlow is slow for some reasons yet. I originally thought we re-shape a lot because of syntax highlighting and auto-linkify, but shaping seems to be very fast in this case. % export CPUPROFILE_FREQUENCY=1000 % $OUT/chrome --enable-blink-features=LayoutNG --enable-profiling --profiling-at-start=renderer --no-sandbox https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/layout/layout_object.h
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Aug 27
The following revision refers to this bug: https://chromium.googlesource.com/chromium/src.git/+/229c8737a637b6d9b82e6fc2748c5574a16b27f1 commit 229c8737a637b6d9b82e6fc2748c5574a16b27f1 Author: Christian Biesinger <cbiesinger@chromium.org> Date: Mon Aug 27 18:18:31 2018 [layoutng] Restore a legacy layout optimization When we do have percentage descendants, we need to force an extra layout when applying stretch alignment, because the flexbox height is now definite (per https://drafts.csswg.org/css-flexbox/#algo-stretch) LayoutNG never set the "has percentage descendants" flag, so we could not skip this extra layout when there are none. We instead had a different optimization that addresses the case where the height was already definite. This patch makes it so that NG does set the flag and makes flexbox use this optimization in NG as well. This has the nice side effect of fixing two tests, in addition to the performance improvement, because we now correctly handle the case of legacy flexbox -> legacy flexbox -> NG block -> NG percentage sized, where the outer flexbox now knows it needs to redo layout in this case (see crbug.com/876459 for more details) Performance improvements according to https://pinpoint-dot-chromeperf.appspot.com/job/15b736ee640000: flexbox-lots-of-data +43.9% flexbox-with-stretch-layout +851.2% Bug: 875147, 876459 Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng Change-Id: I535f0c62993f4cdc03f15cdf91efe300989e43b2 Reviewed-on: https://chromium-review.googlesource.com/1190246 Commit-Queue: Christian Biesinger <cbiesinger@chromium.org> Reviewed-by: Emil A Eklund <eae@chromium.org> Cr-Commit-Position: refs/heads/master@{#586318} [modify] https://crrev.com/229c8737a637b6d9b82e6fc2748c5574a16b27f1/third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG [modify] https://crrev.com/229c8737a637b6d9b82e6fc2748c5574a16b27f1/third_party/blink/renderer/core/layout/layout_flexible_box.cc [modify] https://crrev.com/229c8737a637b6d9b82e6fc2748c5574a16b27f1/third_party/blink/renderer/core/layout/layout_flexible_box.h [modify] https://crrev.com/229c8737a637b6d9b82e6fc2748c5574a16b27f1/third_party/blink/renderer/core/layout/ng/ng_length_utils.cc |
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Comment 1 by cbiesin...@chromium.org
, Aug 17