1607846 - Applying outline-style: auto to a large number of elements makes WR scrolling unusable

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, task)

Description

[Emilio Cobos Álvarez (:emilio)]

STR:

• Enable layout.css.outline-style-auto.enabled (or wait for bug 1031664 to be landed, which I plan to do not long from now).
• Apply this rule to any page with the inspector: * { outline: 1px auto }.
• Try to scroll.

ER:

• Scrolling is somewhat usable.

AR:

• WebRender becomes terribly slow, to the point you can't scroll.

Comment 1

[Emilio Cobos Álvarez (:emilio)]

Here's a profile of scrolling on this page which shows the 500ms+ CONTENT_FRAME_TIMEs: https://perfht.ml/39TkeEE

It seems we spend a bunch of time waiting on the GPU process, but not doing much?

Comment 2

[Emilio Cobos Álvarez (:emilio)]

It's unclear to me what is the GPU process waiting for... Nical, am I missing any thread in the profiler or something?

Comment 3

[Jeff Muizelaar [:jrmuizel]]

Can you add WrWorker to the list of threads?

Comment 4

[Emilio Cobos Álvarez (:emilio)]

Like this? https://perfht.ml/2N8oKFJ

Comment 5

[Jeff Muizelaar [:jrmuizel]]

Yeah. It looks like we're spending all of our time in memmove. We seem to be recording theme bitmaps into blobs and then the recording is just memoving out of them or something like that. We're supposed to avoid recording widget drawing as blobs. Perhaps that's not happening here.

Comment 6

[Jeff Muizelaar [:jrmuizel]]

https://searchfox.org/mozilla-central/source/gfx/layers/wr/WebRenderCommandBuilder.cpp#2093

Are the outlines nsDisplayThemedBackground or nsDisplayButtonBorder?

Comment 7

[Emilio Cobos Álvarez (:emilio)]

They are nsDisplayOutline. This is the code path that triggers the blob: https://searchfox.org/mozilla-central/rev/be7d1f2d52dd9474ca2df145190a817614c924e4/layout/painting/nsDisplayList.cpp#5438

Comment 8

[Emilio Cobos Álvarez (:emilio)]

Conceptually they're very similar to nsDisplayThemedBackground though, I guess.

Comment 9

[Emilio Cobos Álvarez (:emilio)]

Should I just override that to return true and see how it looks like?

Comment 10

[Emilio Cobos Álvarez (:emilio)]

It does work much better indeed.

Comment 11

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1607846 - Make WebRender paint themed outlines in the content process. r=jrmuizel

Similar to how we paint themed borders and backgrounds.

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/47d6ea69c274
Make WebRender paint themed outlines in the content process. r=jrmuizel

Comment 13

[Razvan Maries]

Backed out for perma fails on nsDisplayList.h.

Push with failure: https://treeherder.mozilla.org/#/jobs?repo=autoland&selectedJob=284080994&resultStatus=success%2Ctestfailed%2Cbusted%2Cexception&searchStr=os%2Cx%2C10.14%2Cdebug%2Cmochitests%2Ctest-macosx1014-64%2Fdebug-mochitest-devtools-chrome-e10s-7%2Cm%28dt7%29&revision=47d6ea69c2749e5af5b0d30ad38f601317427f9f

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=284080994&repo=autoland&lineNumber=1140

Later edit.
Also caused: https://treeherder.mozilla.org/#/jobs?repo=autoland&selectedJob=284082963&resultStatus=pending%2Crunning%2Csuccess%2Ctestfailed%2Cbusted%2Cexception&fromchange=95a6f05099b72e4edabcf6cf6811ae1822c4900a&searchStr=android%2C7.0%2Cx86-64%2Cdebug%2Creftests%2Ctest-android-em-7.0-x86_64%2Fdebug-geckoview-reftest-e10s-2%2Cr%28r2%29

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=284082963&repo=autoland&lineNumber=1502

Backout: https://hg.mozilla.org/integration/autoland/rev/e14d491c51f7d3d0236383c6bfcb4a7266562892

Comment 14

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1607846 - Cleanup a bit usage of MustPaintOnContentSide(). r=jrmuizel

This is a pre-requisite cleanup, as the FrameLayerBuilder code ends up calling
this unconditionally, and thus the assertion on the other patch can end up
failing. Hopefully it's dead code, though, so no big deal.

Tweak the WebRender code to avoid two virtual calls in the common path, too.

Comment 15

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/e87b85be662d
Cleanup a bit usage of MustPaintOnContentSide(). r=jrmuizel

Comment 16

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/adeaa48edc50
Make WebRender paint themed outlines in the content process. r=jrmuizel

Comment 17

[Andreea Pavel [:apavel]]

https://hg.mozilla.org/mozilla-central/rev/e87b85be662d
https://hg.mozilla.org/mozilla-central/rev/adeaa48edc50