2028752 - 33% regression on Ares6-Basic-firstiteration on 1Apr2026

Status: RESOLVED DUPLICATE of bug 2029129

(Core :: JavaScript Engine, defect)

Description

[Mayank Bansal]

I noticed some spikes on this test. All the changelogs had Bug 2027803. I triggered some backfills that confirmed my suspicion.

First regression due to first landing
Return to baseline due to backout
Second regression
return to baseline after backout
Third and final regression

Alert triggered due to the manual backfills: https://treeherder.mozilla.org/perfherder/alerts?id=49415

Comment 1

[Mayank Bansal]

I see this regression only on Linux, and only on the browser test. I dont see the regression on sm-shell tests.

Comment 2

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 2027803

Comment 3

[Tooru Fujisawa [:arai]]

most likely I'll accept the regression, but we can wait for other performance results as well.
The performance improvements are confirmed on other browsertime page load tests.

Comment 4

[Tooru Fujisawa [:arai]]

At least locally, I observe the opposite effect on linux.
The Basic_firstIteration score gets improved from 14.85 to 13.39.
So this won't be something worrisome anyway.

Comment 5

[Florin Bilt]

Thank you for reporting this.

This regression bug does not fully follow our current procedures, as it contains incomplete information and some details that appear to be incorrect.
Because of this, I will create a new regression ticket with the correct information, and I will close this as a duplicate.