1390228 - 3.33% sessionrestore_many_windows (linux64) regression on push f7e05dffb1ab4e0b9ed46fa2350c3b5fd4b9efe4 (Thu Aug 10 2017)

Status: RESOLVED WONTFIX

(Firefox :: Session Restore, defect)

Description

[Joel Maher ( :jmaher ) (UTC -8)]

Talos has detected a Firefox performance regression from push:

https://hg.mozilla.org/releases/mozilla-beta/pushloghtml?fromchange=2638feb177dd9104a3887fae2ce05931a6b41d6c&tochange=f7e05dffb1ab4e0b9ed46fa2350c3b5fd4b9efe4

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

Regressions:

  3%  sessionrestore_many_windows linux64 opt e10s     1,554.50 -> 1,606.33


You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=8764

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

[Joel Maher ( :jmaher ) (UTC -8)]

::dao, this landed recently and I see you authored the patch.  This is on mozilla-beta and I don't see a matching regression on m-c.- is this expected to regression mozilla-beta?

Comment 2

[Joel Maher ( :jmaher ) (UTC -8)]

oddly enough, both of these regressions have gone away after seeing this multi-patch commit land on beta:
https://hg.mozilla.org/releases/mozilla-beta/pushloghtml?fromchange=7f3005046367008a49b33c00b53eb077451ccca4&tochange=6ea7b3eb8990bb0f7a16119f8545bcf429d88131

Comment 3

[Dão Gottwald [:dao]]

Some sessionstore perf impact wouldn't be too surprising and unavoidable for the time being since we had to disable a feature. But I also think sessionrestore_many_windows isn't very reliable.