1442139 - 9.83% tp5o_webext responsiveness (linux64) regression on push 724b51d7263fad10ec605a42db433fb784bba43e (Tue Feb 27 2018)

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Ionuț Goldan [:igoldan]]

Talos has detected a Firefox performance regression from push:

https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?changeset=724b51d7263fad10ec605a42db433fb784bba43e

As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

 10%  tp5o_webext responsiveness linux64 opt e10s stylo     1.85 -> 2.04


You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=11802

On the page above you can see an alert for each affected platform as well as a link to a graph showing the history of scores for this test. There is also a link to a treeherder page showing the Talos jobs in a pushlog format.

To learn more about the regressing test(s), please see: https://wiki.mozilla.org/Buildbot/Talos/Tests

For information on reproducing and debugging the regression, either on try or locally, see: https://wiki.mozilla.org/Buildbot/Talos/Running

*** Please let us know your plans within 3 business days, or the offending patch(es) will be backed out! ***

Our wiki page outlines the common responses and expectations: https://wiki.mozilla.org/Buildbot/Talos/RegressionBugsHandling

Comment 1

[Ionuț Goldan [:igoldan]]

:jonco This regression happens only on Linux x64 OPT builds. The equivalent PGO builds aren't affected at all, nor are the other platforms.
Performance bugs like these usually end up as WONTFIXES or INVALID. Still, please take a quick look over this, in case you notice something weird.

Comment 2

[Ionuț Goldan [:igoldan]]

Also, the regression isn't that big, rather a 2%; I noticed you did some previous changes which improved performance for a short while and then bug 1439284 showed up.

Comment 3

[Jon Coppeard (:jonco)]

The push that produced the improvement was badly broken, and this push was the fix.

I am surprised that this didn't go back to the previous baseline.  But there's nothing to do here.