1731536 - 11.18 - 10.26% instagram fnbpaint / google-slides fcp + 2 more (Windows) regression on Thu September 16 2021

Status: RESOLVED INVALID

(Core :: Performance: Navigation, defect)

Description

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

Perfherder has detected a browsertime performance regression from push 8e8744f33c56b5423347895c709dc73318bf8803. 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)
11%	instagram fnbpaint	windows10-64-shippable-qr	fission warm webrender	151.62 -> 168.58
10%	instagram fcp	windows10-64-shippable-qr	fission warm webrender	150.54 -> 166.33
10%	google-slides fnbpaint	windows10-64-shippable-qr	fission warm webrender	230.67 -> 254.50
10%	google-slides fcp	windows10-64-shippable-qr	fission warm webrender	222.92 -> 245.79

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
10%	google-slides dcf	windows10-64-shippable-qr	fission warm webrender	826.33 -> 740.92

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

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1730834

Comment 2

[Emilio Cobos Álvarez [:emilio]]

How sure are we of the regressing range? My patch removed one line of code which isn't executed when I run:

./mach raptor --browsertime -t instagram --verbose --debug

So I'm not sure how to debug this further.

Comment 3

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

I double checked the regression range and seems like bug 1727158 is the culprit.

Comment 4

[Emilio Cobos Álvarez [:emilio]]

Phew, thanks!