Talos has detected a Firefox performance regression from push: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=62453a779f13a47cd76eb527bc948e6d42e8f60f&tochange=e3dae8b7e2f2f25cb67c27ea54ddb967b304f58b As author of one of the patches included in that push, we need your help to address this regression. Regressions: 5% tpaint windows10-64 opt e10s stylo 250.58 -> 263.17 You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=12089 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

:xidorn This regression happens only on Windows 10 OPT build. PGO build is not affected and neither are the other platforms.

I guess that happens because the extra resize code path there can occasionally trigger an extra resize somehow in some condition. I wouldn't worry about that, though, because that patch is a prerequisite for bug 1439875, and that bug should eliminate any extra cost caused by additional resize in the window open path as a whole. Also, I don't think we really care about regression on windows opt build, do we? We should only be shipping pgo builds I suppose.

(In reply to Xidorn Quan [:xidorn] UTC+10 from comment #2) > Also, I don't think we really care about regression on windows opt build, do > we? We should only be shipping pgo builds I suppose. No, we're very interested in the PGO builds. OPT based results are just an extra eye on the perf status.

(In reply to Ionuț Goldan [:igoldan], Performance Sheriffing from comment #3) > (In reply to Xidorn Quan [:xidorn] UTC+10 from comment #2) > > Also, I don't think we really care about regression on windows opt build, do > > we? We should only be shipping pgo builds I suppose. > > No, we're very interested in the PGO builds. OPT based results are just an > extra eye on the perf status. So, can we just close this bug then?

(In reply to Xidorn Quan [:xidorn] UTC+10 from comment #4) > (In reply to Ionuț Goldan [:igoldan], Performance Sheriffing from comment #3) > > (In reply to Xidorn Quan [:xidorn] UTC+10 from comment #2) > > > Also, I don't think we really care about regression on windows opt build, do > > > we? We should only be shipping pgo builds I suppose. > > > > No, we're very interested in the PGO builds. OPT based results are just an > > extra eye on the perf status. > > So, can we just close this bug then? Yes, we should.