1885556 - 4.62 - 4.32% fandom ContentfulSpeedIndex / fandom loadtime + 1 more (Linux) regression on Fri March 8 2024

Status: RESOLVED WONTFIX

(Core :: Networking: DNS, defect)

Description

[Alex Finder|PTO, returning August 18th]

Perfherder has detected a browsertime performance regression from push 8a936faee760859d530e2fbc7d8ac3d0294385b5. 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
5%	fandom ContentfulSpeedIndex	linux1804-64-shippable-qr	bytecode-cached cold fission webrender	627.82 -> 656.80	Before/After
4%	fandom FirstVisualChange	linux1804-64-shippable-qr	bytecode-cached cold fission webrender	407.75 -> 425.37	Before/After
4%	fandom loadtime	linux1804-64-shippable-qr	bytecode-cached cold fission webrender	1,284.11 -> 1,339.64	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 41815

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Comment 1

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

Set release status flags based on info from the regressing bug 1874464

Comment 2

[Valentin Gosu [:valentin] (he/him)]

I think this is just a consequence of also doing HTTPS lookups.
It's already the case when DoH is enabled - this just opened up that code path in performance tests as well.
Bug 1888815 should improve things slightly, by making sure we use the cache when appropriate.
But otherwise I don't know if there's much we can do about it.