1906325 - 4.28 - 2.3% google-slides LastVisualChange / google-slides LastVisualChange + 5 more (OSX, Windows) regression on Tue June 25 2024

Status: NEW

(Core :: Graphics: WebRender, defect)

Description

[Andra Esanu (needinfo me)]

Perfherder has detected a browsertime performance regression from push beec388d4b0e6a50ac243ed86c0e3f1f48cbe744. As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

Ratio	Test	Platform	Options	Absolute values (old vs new)	Performance Profiles
4%	google-slides LastVisualChange	windows10-64-shippable-qr	bytecode-cached fission warm webrender	1,568.57 -> 1,635.70	Before/After
3%	google-slides LastVisualChange	macosx1015-64-shippable-qr	bytecode-cached fission warm webrender	1,383.48 -> 1,427.54	Before/After
3%	google-slides LastVisualChange	macosx1015-64-shippable-qr	cold fission webrender	2,395.85 -> 2,468.42	Before/After
3%	google-slides LastVisualChange	macosx1015-64-shippable-qr	bytecode-cached cold fission webrender	2,422.63 -> 2,494.37	Before/After
3%	google-slides LastVisualChange	macosx1015-64-shippable-qr	fission warm webrender	1,889.30 -> 1,944.58	Before/After
2%	google-slides LastVisualChange	windows10-64-shippable-qr	bytecode-cached cold fission webrender	2,620.79 -> 2,683.86	Before/After
2%	google-slides LastVisualChange	windows10-64-shippable-qr	bytecode-cached cold fission webrender	2,622.25 -> 2,682.45	Before/After

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests. Please follow our guide to handling regression bugs and let us know your plans within 3 business days, or the patch(es) may be backed out in accordance with our regression policy.

If you need the profiling jobs you can trigger them yourself from treeherder job view or ask a sheriff to do that for you.

You can run these tests on try with ./mach try perf --alert 1025

For more information on performance sheriffing please see our FAQ.

Comment 1

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1896503

Comment 2

[Ashley Hale [:ahale]]

I have a guess that this is partially clipped rects which I'm not handling elegantly in get_surface_rects in WebRender at this time, so I am planning to start optimizing that function on Monday, which should also address Bug 1905611.

It could also be the extra picture copy the SVGFE code does if it needs to crop the final subregion, which I could address by analyzing the DAG backwards to find exact subregions needed as input for each node, rather than only forwards as it does now, but that is a higher risk change to explore.

Comment 3

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1896503

Comment 4

[Donal Meehan [:dmeehan]]

:ahale, next week is the final week of beta for Fx129. Do you plan on fixing this in time for release?
https://whattrainisitnow.com/release/?version=129

Comment 5

[Ashley Hale [:ahale]]

The feature is controlled by a pref that is true only in nightly (at least after a fix in https://phabricator.services.mozilla.com/D215720 ) so I'm not sure it's relevant to beta.

I have a fix out for review that may fix this performance regression while also fixing a regression with rendering resolution on large stacking contexts https://phabricator.services.mozilla.com/D216637

Comment 6

[Ashley Hale [:ahale]]

Note that this should be faster as of https://phabricator.services.mozilla.com/D216637 but it may still regress performance as there is one more copy I want to optimize away in a follow-up.