1548824 - 2.21% tscrollx (windows10-64-shippable-qr) regression on push 09753a1a153d348d456a0c785fcffeb9a77dd065 (Wed May 1 2019)

Status: RESOLVED WONTFIX

(Core :: Graphics: WebRender, defect, P3)

Description

[Cristina Coroiu [:ccoroiu]]

Talos has detected a Firefox performance regression from push:

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=f08eb5f2a017499fc2d1b8704fc1c62ffdca5f35&tochange=9ec9c4c0be3b7ab74b1ebaeb921ec62afa7691cd

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

Regressions:

2% tscrollx windows10-64-shippable-qr opt e10s stylo 0.94 -> 0.97

You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=20752

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/Performance_sheriffing/Talos/Tests

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

Comment 1

[Glenn Watson [:gw]]

This is (somewhat) expected right now. I'm landing small patches incrementally towards the overall goals listed in https://bugzilla.mozilla.org/show_bug.cgi?id=1536360.

I think the unit for this test is ms, so since both numbers are < 1ms (out of a frame budget of 16.67ms) any small regression can show up a a large percentage change here.

Given that, I think this regression is fine to ignore for now, although we might want to reconsider once all of the picture caching improvement work linked above lands.

CC'ing Matt to double check if the statements above seem reasonable.

Comment 2

[Matt Woodrow (:mattwoodrow)]

Yeah that's correct, the result is ms, so this is a regression of 0.03ms/frame. Definitely not worth worrying about until we get to the final state of picture caching.

Comment 3

[BugBot [:suhaib / :marco/ :calixte]]

The priority flag is not set for this bug.
:jbonisteel, could you have a look please?

For more information, please visit auto_nag documentation.

Comment 4

[Glenn Watson [:gw]]

This happened a long time ago.