Talos has detected a Firefox performance regression from push:

https://hg.mozilla.org/integration/autoland/pushloghtml?changeset=ab9df6cf0f4fbd1073e776dfa89a79b8d9febf07

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

Regressions:

18% glterrain linux64-shippable-qr opt e10s stylo 4.89 -> 5.79
18% glterrain linux64-shippable-qr opt e10s stylo 4.86 -> 5.75

You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=23078

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/TestEngineering/Performance/Talos

For information on reproducing and debugging the regression, either on try or locally, see: https://wiki.mozilla.org/TestEngineering/Performance/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/TestEngineering/Performance/Talos/RegressionBugsHandling

I took a look at the history graph of the talos test above (https://treeherder.mozilla.org/perf.html#/graphs?timerange=1209600&series=autoland,1930103,1,1&series=mozilla-inbound,9f70a793d155643a72a846361151d8ec69d06126,1,1).

What it looks like is:

• 5.8 is the "normal" result for this test case.
• On Sept 11 the performance improved significantly, giving a result of 4.8.
• On Sept 13 the performance returned to the "normal" result of ~5.7.

I think what has occurred here is that the performance improvement was a bug, where the webgl canvas was not being rendered correctly due to a regression a few days ago. This was then fixed yesterday, which has made the test return to the normal result.

Does that match your interpretation of the graph above? If so, I think we can close this as invalid?

Hi Glenn,
Yes, i'm ok with this interpretation and will mark the alert accordingly.
Thank you!