1678543 - 4.84 - 8.77% startup_about_home_paint_realworld_webextensions (windows10-64-shippable-qr) regression on push 6ca8cea4044a74c89e0137660c243bd542714abc (Mon November 16 2020)

Status: ASSIGNED

(Firefox :: Session Restore, defect)

Description

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

Perfherder has detected a talos performance regression from push 6ca8cea4044a74c89e0137660c243bd542714abc. 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)
9%	startup_about_home_paint_realworld_webextensions	startup_about_home_paint_realworld_webextensions	windows10-64-shippable-qr	e10s stylo webrender	572.75 -> 623.00
5%	startup_about_home_paint_realworld_webextensions	startup_about_home_paint_realworld_webextensions	windows10-64-shippable-qr	e10s stylo webrender	594.50 -> 623.25

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/ :calixte]]

Set release status flags based on info from the regressing bug 1675334

Comment 2

[Nika Layzell [:nika] (ni? for response)]

I'm guessing I caused us to do a process switch later or similar. Will investigate a bit more to figure out what exactly this test is doing.

This probably won't be done until the week after next, due to next week largely being taken off.

Comment 3

[Nika Layzell [:nika] (ni? for response)]

Probably actually regressed by bug 1671983 from the same push

Comment 4

[Nika Layzell [:nika] (ni? for response)]

I've triggered some retries with profiles between these two revisions:

before: https://treeherder.mozilla.org/jobs?repo=autoland&revision=346bbd581eb8d0da384d248bef8a3f4733f4e391&selectedTaskRun=UhGrREZ7RTOb8NA-nQHn4g.0
after: https://treeherder.mozilla.org/jobs?repo=autoland&revision=6ca8cea4044a74c89e0137660c243bd542714abc&selectedTaskRun=byeaJ_3RTdyE6MkCQzcfQg.0

Unfortunately, it seems that running the profiler caused the output parser to break, meaning that you need to open the raw log files in order to get the specific results from these test runs.

I looked at the profiles a bit, and didn't see anything obvious. I can try to give it a more in-depth look after the break.