Closed Bug 1763562 Opened 2 years ago Closed 2 years ago

2.57 - 1.53% stackoverflow fcp / stackoverflow dcf + 2 more (Android) regression on Thu March 24 2022


(Testing :: General, defect)



(firefox-esr91 unaffected, firefox99 unaffected, firefox100 wontfix, firefox101 wontfix, firefox102 wontfix)

Tracking Status
firefox-esr91 --- unaffected
firefox99 --- unaffected
firefox100 --- wontfix
firefox101 --- wontfix
firefox102 --- wontfix


(Reporter: afinder, Unassigned)




(Keywords: perf, perf-alert, regression)

Perfherder has detected a browsertime performance regression from push e4642f25fd379650da436c21ef0d9cd2c2f18506. As author of one of the patches included in that push, we need your help to address this regression.


Ratio Test Platform Options Absolute values (old vs new)
3% stackoverflow fcp android-hw-g5-7-0-arm7-shippable-qr warm webrender 404.12 -> 414.50
2% stackoverflow fnbpaint android-hw-g5-7-0-arm7-shippable-qr warm webrender 507.40 -> 517.79
2% stackoverflow dcf android-hw-g5-7-0-arm7-shippable-qr warm webrender 512.15 -> 522.50
2% stackoverflow dcf android-hw-g5-7-0-arm7-shippable-qr warm webrender 513.73 -> 521.58

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.

Flags: needinfo?(jdescottes)

Set release status flags based on info from the regressing bug 1760259

Thanks for filing.

This most likely comes from the first patch from the stack where we are applying our preferences earlier than before. As usual with marionette related changes, this normally doesn't relate to a real regression for end users, as they will not run with marionette enabled.

I have checked a few other tests (eg reddit fcp opt warm webrender), on the same platform, and they don't show a similar regression. If the regression was purely about the time needed to set preferences, I imagine this would have impacted other tests. Since it's not the case, it might be that one of the marionette recommended preferences, now set earlier, impacts the load for those tests.

I will first verify that it's really about the changeset I suspect, then we might bisect to see if it's a specific preference or not.

Has Regression Range: --- → yes

I can confirm this is from the first patch in the stack ; the following try push backed out the second patch and still shows the performance regression:

Flags: needinfo?(jdescottes)

Hi Julian, any updates on this bug?

Hi! We discussed this bug in triage a few weeks ago and I should have updated it.

Mainly, this is not a regression which can impact end users since the code involved is only triggered in automation.
It could be interesting to find which preference caused this, but this is not going to be a priority for now.

Should we close as WONTFIX, I doubt we will get to it soon.

Flags: needinfo?(jdescottes)
Closed: 2 years ago
Resolution: --- → WONTFIX
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