1269796 - 2.15 - 3.5% sessionrestore / sessionrestore_no_auto_restore / tpaint / ts_paint (windows7-32, windows8-64, windowsxp) regression on push edb632ad80c4 (Thu Apr 28 2016)

Status: RESOLVED FIXED

(Core :: JavaScript: GC, defect)

Description

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

Talos has detected a Firefox performance regression from push edb632ad80c4:
https://hg.mozilla.org/integration/mozilla-inbound/rev/edb632ad80c4ad653972056ff78578a129a35506

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

This is a list of all known regressions and improvements related to the push:
https://treeherder.mozilla.org/perf.html#/alerts?id=1051

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#ts_paint
https://wiki.mozilla.org/Buildbot/Talos/Tests#sessionrestore.2Fsessionrestore_no_auto_restore
https://wiki.mozilla.org/Buildbot/Talos/Tests#tpaint

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 win64,win32 -u none -t other[Windows 8,Windows XP,Windows 7],other-e10s[Windows 8,Windows XP,Windows 7] --rebuild 5  # add "mozharness: --spsProfile" to generate profile data

(we suggest --rebuild 5 to be more confident in the results)

To run the test locally and do a more in-depth investigation, first set up a local Talos environment:
https://wiki.mozilla.lorg/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 ts_paint:sessionrestore_no_auto_restore:sessionrestore:tpaint

(add --e10s to run tests in e10s mode)

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

I did a lot of retriggers here and the compare view for the most part matches the alerts generated:
https://treeherder.mozilla.org/perf.html#/compare?originalProject=mozilla-inbound&originalRevision=ac1770eeff8a&newProject=mozilla-inbound&newRevision=edb632ad80c4&framework=1

:terrence, I see you authored this, can you take this bug and help figure out what the root cause is and if there is anything we can do to reduce this regression?

Comment 2

[Terrence Cole [:terrence]]

Backed out the offending bug. We'll have to wait on the other pieces of architectural work to land first.

Comment 3

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

improvement alerts are coming in:
https://treeherder.mozilla.org/perf.html#/alerts?id=1094