1808018 - 6.33% instagram PerceptualSpeedIndex (Windows) regression on Wed December 21 2022

Status: RESOLVED INCOMPLETE

(Core :: JavaScript Engine, defect)

Description

[Alex Finder|PTO, back on May 7th]

Perfherder has detected a browsertime performance regression from push 60af383da56bac4e56d9ebe765fb0a104df11f0f. 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
6%	instagram PerceptualSpeedIndex	windows10-64-shippable-qr	bytecode-cached fission warm webrender	285.83 -> 303.92	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 offending 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 1805856

Comment 2

[Ted Campbell [:tcampbell]]

The attached profiles are broken and do not currently load in the Gecko Profiler. It sounds like the profiler folks will land a workaround at some point to fix this.

I used try to simulate backing out the patch and there is zero impact to the instagram PerceptualSpeedIndex number, so there is either a false positive or the issue is unrelated to the code itself. Closing this JavaScript bug as incomplete since there does not seem to be evidence of a JS issue here.

https://treeherder.mozilla.org/perfherder/compare?originalProject=try&originalRevision=bed2704d890f901ba0800af0b75d3b83bafd7ec4&newProject=try&newRevision=7795b1eb35549bccb28d78a7fe80aec0e6033a70&framework=13&page=1&filter=PerceptualSpeedIndex