2057452 - Intermittent tile-shaped glitches with Webrender on Metal ANGLE

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Jamie Nicol [:jnicol]]

Markus has seen this. I think I have once or twice myself.

I think we're missing some synchronisation between rendering the picture cache tiles and compositing them. We call glFlush() here but presumably that is not enough on Metal ANGLE.

I'm going to try waiting on a EGL_SYNC_METAL_COMMANDS_SCHEDULED_ANGLE sync instead.

Comment 1

[Jamie Nicol [:jnicol]]

Attachment: Bug 2057452 - Wait for commands to be scheduled before compositing on Metal ANGLE. r?#gfx-reviewers

RenderCompositorNative calls glFlush() prior to compositing its
layers. This is enough synchronisation on native GL on macOS, but on
Metal ANGLE we have observed intermittent tile shaped glitches.

It's hard to reproduce reliably, but as a speculative fix try waiting
for the prior commands to be scheduled using the
ANGLE_wait_until_work_scheduled extension.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/9bfbbd8a493e
https://hg.mozilla.org/integration/autoland/rev/157111f7fc91
Wait for commands to be scheduled before compositing on Metal ANGLE. r=gfx-reviewers,bradwerth

Comment 3

[Silaghi Andreea]

https://hg.mozilla.org/mozilla-central/rev/157111f7fc91

Comment 4

[Jamie Nicol [:jnicol]]

I discovered this bug could be reproduced trivially on this page: https://registry.khronos.org/webgl/sdk/tests/extra/workload-simulator.html?animate&glWork&drawCalls=10000&x100

with animation enabled and a massive draw call count. then pressing cmd+L to activate the URL bar dropdown. 4 out of 5 times I see the glitches on my M5 Macbook pro.

And with the patch I can no longer reproduce. There could of course be other scenarios in which it reproduces, so will keep an eye out. But that's a good sign.

Comment 5

[Markus Stange [:mstange]]

I also haven't seen these glitches anymore since this fix landed. Looks good to me!