1715939 - 18.48 - 12.81% about_preferences_basic / about_preferences_basic + 1 more (Linux) regression on Tue June 8 2021

Status: RESOLVED WONTFIX

(Core :: DOM: Navigation, defect, P5)

Description

[Alexandru Ionescu (needinfo me) [:alexandrui]]

Perfherder has detected a talos performance regression from push 434d5ad2b9ae6212b8b5ea93a64ab4e77adf6c23. As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

Ratio	Suite	Test	Platform	Options	Absolute values (old vs new)
18%	about_preferences_basic (docs)		linux1804-64-shippable	e10s stylo	142.09 -> 168.36
14%	about_preferences_basic (docs)		linux1804-64-shippable	e10s stylo	147.28 -> 167.52
13%	about_preferences_basic (docs)		linux1804-64-shippable-qr	e10s stylo webrender-sw	144.29 -> 162.77

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) will be backed out in accordance with our regression policy.

For more information on performance sheriffing please see our FAQ.

Comment 1

[Olli Pettay [:smaug][[e-mail]]]

Hmm, that in unexpected. Is the test doing something unrealistic like set document title and then same document navigation in a loop?
The patch does fix a real bug with title + session history handling.

Comment 2

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1706167

Comment 3

[Olli Pettay [:smaug][[e-mail]]]

FWIW, I don't expect there to be a "fix" there.

Comment 4

[Chris Peterson [:cpeterson]]

(In reply to Olli Pettay [:smaug] from comment #3)

FWIW, I don't expect there to be a "fix" there.

In that case, I'll clear the Fission Milestone flag so this regression doesn't block Fission.

Comment 5

[Chris Peterson [:cpeterson]]

(In reply to Olli Pettay [:smaug] from comment #1)

Hmm, that in unexpected. Is the test doing something unrealistic like set document title and then same document navigation in a loop?
The patch does fix a real bug with title + session history handling.

Olli will decide how to triage this bug after receiving needinfo about what this test is doing.

Comment 6

[Jared Wein [:jaws] (please needinfo? me)]

(In reply to Olli Pettay [:smaug] from comment #1)

Hmm, that in unexpected. Is the test doing something unrealistic like set document title and then same document navigation in a loop?
The patch does fix a real bug with title + session history handling.

The test navigates to each preference category with about:blank visits in-between. Preference categories are visited by appending a hash to the URL (about:preferences#privacy, for example). When about:preferences is loaded, we look at the hash to determine which elements to show (the preferences are implemented as one long page that hides/shows the requested content). We then call window.location.replaceState[1] to handle cases where the category name provided was not a human-friendly name (we have both human-friendly and internal category names).

Likely this issue is happening at the replaceState call, and we could optimize this by not calling replaceState in the event that the category name didn't need to be converted to a "friendly" name.

[1] https://searchfox.org/mozilla-central/rev/4f05a46731c1f7f111ec7a41ce38a34594aa0d37/browser/components/preferences/preferences.js#240,270,281

Comment 7

[Alex Finder]

Hi Alex! Linked alert for this defect is no longer accessible.