2046376 - 21.83% perf_reftest some-descendants-1.html (Linux) regression on Wed June 3 2026

Status: RESOLVED FIXED

(Firefox Build System :: Toolchains, defect)

Description

[Treeherder Bug Filer]

Perfherder has detected a talos performance regression from push 7ffb408bfa80dc47e904cb74f918181502217b2a. As author of one of the patches included in that push, we need your help to address this regression.

Please acknowledge, and begin investigating this alert within 3 business days, or the patch(es) may be backed out in accordance with our regression policy.

Regression	Test	Platform	Options	Absolute values [old vs new]
22%	perf_reftest some-descendants-1.html (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	4.98 ms -> 6.07 ms

Support & Actionable Steps

For questions, please contact [e-mail]. You can also find help on Slack (#perf-help) or Matrix (#perftest).

Action guide details:

• See the guide to handling regression bugs for investigation steps.
• Review the alert summary for affected tests, graphs, and comparisons.
• Check the PerfCompare results.
• Tests on Try: Run all tests using ./mach try perf --alert 50754 (See documentation link for details).
• Profiling jobs: Trigger jobs from Treeherder job view or request them from [e-mail].

Comment 1

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 2002120

Comment 2

[Mike Hommey [:glandium]]

Attachment: Bug 2046376 - Upgrade smallvec to 1.15.2.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/fd5974bd41b4
https://hg.mozilla.org/mozilla-central/rev/53410370cee0
Upgrade smallvec to 1.15.2. r=emilio,supply-chain-reviewers

Comment 4

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/53410370cee0

Comment 7

[Florin Bilt]

(In reply to Norisz Fay [:noriszfay] from comment #4)

https://hg.mozilla.org/mozilla-central/rev/53410370cee0

Perfherder has detected a browsertime performance change from push 53410370cee027ab4bf216cdb492615badf30fe5.

No action is required from the author; this comment is provided for informational purposes only.

Improvement	Test	Platform	Options	Absolute values [old vs new]
7%	jetstream3 cdjs-Worst (doc)	macosx1470-64-shippable	fission webrender	88.63 ms -> 82.08 ms
7%	jetstream3 cdjs-Geometric (doc)	macosx1470-64-shippable	fission webrender	55.90 score -> 59.75 score
6%	jetstream3 cdjs-Average (doc)	macosx1470-64-shippable	fission webrender	85.93 ms -> 80.69 ms
6%	jetstream3 cdjs-Average (doc)	macosx1500-aarch64-shippable	fission webrender	24.87 ms -> 23.48 ms

Need Help or Information?

If you have any questions, please reach out to [e-mail]. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.

Comment 8

[Performance Sheriff Bot]

Perfherder has detected a talos performance change from push 53410370cee027ab4bf216cdb492615badf30fe5.

No action is required from the author; this comment is provided for informational purposes only.

Improvements	Test	Platform	Options	Absolute values [old vs new]
16%	perf_reftest some-descendants-1.html (doc)	linux2404-64-shippable	e10s fission stylo webrender	6.10 ms -> 5.12 ms
15%	perf_reftest some-descendants-1.html (doc)	linux2404-64-shippable	e10s fission stylo webrender-sw	6.12 ms -> 5.20 ms
13%	perf_reftest some-descendants-1.html (doc)	macosx1470-64-shippable	e10s fission stylo webrender-sw	5.72 ms -> 4.96 ms
8%	perf_reftest_singletons append-nth-edge-has-pseudo.html (doc)	macosx1470-64-shippable	e10s fission stylo webrender	9.13 ms -> 8.38 ms
7%	perf_reftest_singletons nth-index-2.html (doc)	linux2404-64-shippable	e10s fission stylo webrender	1.28 ms -> 1.19 ms
...	...	...	...	...
6%	perf_reftest_singletons nth-index-1.html (doc)	macosx1470-64-shippable	e10s fission stylo webrender	1.48 ms -> 1.38 ms

Need Help or Information?

If you have any questions, please reach out to [e-mail]. Alternatively, you can find help on Slack by joining #perf-help, and on Matrix you can find help by joining #perftest.

Details of the alert can be found in the alert summary, including links to graphs and comparisons for each of the affected tests.