1479353 - 3.07 - 3.69% sessionrestore_many_windows (linux64) regression on push c034e7ddbacdbe80ec8ce5b844e4299fcac9287c (Thu Jul 26 2018)

Status: RESOLVED WONTFIX

(WebExtensions :: General, defect)

Description

[Ionuț Goldan [:igoldan]]

Talos has detected a Firefox performance regression from push:

https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=1c52d8baf78986cb9497d48b8b88291686a681ca&tochange=c034e7ddbacdbe80ec8ce5b844e4299fcac9287c

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

Regressions:

  4%  sessionrestore_many_windows linux64 opt e10s stylo     1,104.17 -> 1,144.92
  3%  sessionrestore_many_windows linux64 pgo e10s stylo     1,032.92 -> 1,064.58

Improvements:

 19%  tp5o_webext responsiveness linux64-qr opt e10s stylo     2.20 -> 1.78


You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=14624

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

[Kris Maglione [:kmag]]

I'm a bit surprised that this caused a regression in this test. My best guess is that the extra process just makes the main process bump into system resource constraints during that test.

But I don't think it's worth worrying about. The over all performance impact of this change is positive, and we've already decided to eat whatever memory and latency increases it requires, both here and on other platforms.