Closed Bug 1527829 Opened 5 years ago Closed 5 years ago

1.5 - 1.68% sessionrestore / ts_paint_webext (linux64-qr) regression on push 87ad4b91e29fb9025d90ceb89a62b5a4eb7d584a (Thu Feb 7 2019)


(Core :: Graphics: WebRender, defect)

Not set





(Reporter: Bebe, Assigned: jrmuizel)



(Keywords: perf, regression, talos-regression)

Talos has detected a Firefox performance regression from push:

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


2% sessionrestore linux64-qr opt e10s stylo 789.54 -> 802.83
2% ts_paint_webext linux64-qr opt e10s stylo 849.79 -> 862.50

You can find links to graphs and comparison views for each of the above tests at:

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:

For information on reproducing and debugging the regression, either on try or locally, see:

*** 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:

Blocks: 1453935, 1521698
Component: General → Graphics: WebRender
Flags: needinfo?(nical.bugzilla)
Flags: needinfo?(aosmond)
Product: Testing → Core
Version: Version 3 → unspecified

This is a pretty surprising regression given the code changes...

(In reply to Jeff Muizelaar [:jrmuizel] from comment #2)

This is a pretty surprising regression given the code changes...

I'm not sure if we have much choice besides swallowing it.

Flags: needinfo?(aosmond)
Assignee: nobody → jmuizelaar

I tried reverting this change. We'll see what the performance numbers look like:

Reverting the change does seem to move the numbers back. Here's a version that only reverts the shader change:

Flags: needinfo?(nical.bugzilla)

The conclusion is that the shader change caused this:

This is pretty surprising. Perhaps we're causing the shader compiler to be sad.

Since this is Linux only, we're not currently shipping on Linux and Linux's ts_paint_webext and sessionrestore numbers are already about twice as bad with WebRender vs non-WebRender I don't think it's worth investigating a <2% regression.

Closed: 5 years ago
Resolution: --- → WONTFIX
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