1246396 - 2-5% Linux 64/Win8/MacOS sessionrestore regression on Mozilla-Inbound (v.47) on February 04, 2016 from push 0579589f4afc564e23c274af7750cd10c724c342

Status: RESOLVED FIXED

(Core :: JavaScript Engine, defect)

Description

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

Talos has detected a Firefox performance regression from your commit 0579589f4afc564e23c274af7750cd10c724c342 in bug 1221144.  We need you to address this regression.

This is a list of all known regressions and improvements related to your bug:
http://alertmanager.allizom.org:8080/alerts.html?rev=0579589f4afc564e23c274af7750cd10c724c342&showAll=1

On the page above you can see Talos 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, please see: https://wiki.mozilla.org/Buildbot/Talos/Tests#sessionrestore.2Fsessionrestore_no_auto_restore

Reproducing and debugging the regression:
If you would like to re-run this Talos test on a potential fix, use try with the following syntax:
try: -b o -p linux64,win64,macosx64 -u none -t other  # add "mozharness: --spsProfile" to generate profile data

To run the test locally and do a more in-depth investigation, first set up a local Talos environment:
https://wiki.mozilla.org/Buildbot/Talos/Running#Running_locally_-_Source_Code

Then run the following command from the directory where you set up Talos:
talos --develop -e <path>/firefox -a sessionrestore

Making a decision:
As the patch author we need your feedback to help us handle this regression.
*** Please let us know your plans by Tuesday, or the offending patch 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)]

I have a compare view of this changeset compared to the previous one:
https://treeherder.mozilla.org/perf.html#/compare?originalProject=mozilla-inbound&originalRevision=73107e62f038&newProject=mozilla-inbound&newRevision=0579589f4afc&framework=1

We have tps improvements which is good as well, but the sessionrestore regressions should be figured out.

:jorendorff, can you take up this bug and let us know what the next steps are by Tuesday?  If you want, I can bisect the set of patches down to the offending one, but I would want to know if each patch can be built independently.

Comment 2

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

backed out:
https://hg.mozilla.org/integration/mozilla-inbound/rev/966f47ed2f25

please run talos on try before pushing again!