1872347 - 21.93 - 12.85% instagram loadtime / instagram LastVisualChange + 3 more (OSX) regression on Mon December 25 2023

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

[Andra Esanu (needinfo me)]

Perfherder has detected a browsertime performance regression from push 4d6294424819e7658e0649e50e2e0c10f8f88b2e. 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
22%	instagram loadtime	macosx1015-64-shippable-qr	fission warm webrender	394.28 -> 480.72	Before/After
19%	instagram SpeedIndex	macosx1015-64-shippable-qr	fission warm webrender	420.02 -> 501.13	Before/After
19%	instagram PerceptualSpeedIndex	macosx1015-64-shippable-qr	fission warm webrender	303.92 -> 361.08	Before/After
19%	instagram largestContentfulPaint	macosx1015-64-shippable-qr	fission warm webrender	496.20 -> 589.46	Before/After
13%	instagram LastVisualChange	macosx1015-64-shippable-qr	fission warm webrender	603.02 -> 680.49	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.

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Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1800641

Comment 2

[Tooru Fujisawa [:arai]]

I've checked profiles, and somehow there's a ~100ms gap in many profiles for the push with cpu=0%, across platform.
The gap doesn't appear in the previous push, so it seems to be introduced by the change.

https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FUZvdlwnBQDSbSrmfUqRyfA%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_instagram.zip/marker-chart/?file=instagram-pageload-warm%2Fpage-cycle-1.json.gz&globalTrackOrder=dwfc0wb&hiddenGlobalTracks=1wa&hiddenLocalTracksByPid=2752-12~2765-0~2753-0~2756-0~2760-0~2767-0~2766-0~2768-0~2757-0~2754-0~2755-0&range=3126m766&thread=e&v=10
https://profiler.firefox.com/from-url/https%3A%2F%2Ffirefox-ci-tc.services.mozilla.com%2Fapi%2Fqueue%2Fv1%2Ftask%2FNeohUJbTRYuEQMQoovKHww%2Fruns%2F0%2Fartifacts%2Fpublic%2Ftest_info%2Fprofile_instagram.zip/marker-chart/?file=instagram-pageload-warm%2Fpage-cycle-1.json.gz&globalTrackOrder=dwfc0wb&hiddenGlobalTracks=1wa&hiddenLocalTracksByPid=2815-12~2819-0~2816-0~2830-0~2820-0~2817-0~2823-0~2828-0~2818-0~2829-0~2831-0&range=3141m824&thread=e&v=10

I'll investigate it, but let's backout the patch for now.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

:nbp, since you are the author of the regressor, bug 1800641, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 4

[Tooru Fujisawa [:arai]]

should be fixed by backout