Bug 224778 – MotionMark's Canvas-Arcs subtest is broken if the GPUProcess is not yet running

• Component: WebKit2
• Status: RESOLVED DUPLICATE

[Chris Dumez]

MotionMark's Canvas-Arcs subtest is broken if the GPUProcess is not yet running.

[Chris Dumez]

Created attachment 426458 [details]
Patch

[Simon Fraser (smfr)]

Comment on attachment 426458 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=426458&action=review

> Source/WebKit/WebProcess/GPU/graphics/RemoteRenderingBackendProxy.cpp:78
> +        // FIXME: This message shouldn't need to be synchronous. However, we seem to get in a bad state when this message is asynchronous and the GPUProcess has just launched.

Would be good to have a bug link here.

[Chris Dumez]

Committed r276271 (236753@main): <https://commits.webkit.org/236753@main>

[Chris Dumez]

It doesn't look like this helped on the bots :/ I may need some help here. I suspect the display list logic either gets into a bad state or is dropping some initial work.

It is fairly easy to get in that bad state if constructing the RemoteRenderingBackendProxy launches the GPUProcess (which I made a lot more common since the GPUProcess is now only launched when needed).

I spent quite some time trying to understand the DisplayList IPC logic but it is fairly complicated.

When running MotionMark's Canvas-Arcs, in the success case, I see RemoteRenderingBackend::didCreateSharedDisplayListHandle() getting called at least 4 times. However, in the failure case, it seems RemoteRenderingBackend::didCreateSharedDisplayListHandle() is only called once. I have no idea why this could be happening. Wenson, do you have any idea?

In both failure and success cases, I see many calls to RemoteRenderingBackend::wakeUpAndApplyDisplayList() and the initialization stage (GPUConnectionToWebProcess::createRenderingBackend & RemoteRenderingBackend::createImageBuffer) looks the same.

[Ryan Haddad]

rdar://76860669

[Chris Dumez]

Reverted r276271 for reason:

It did not fix the Canvas-Arcs subtest on the bots

Committed r276304 (236786@main): <https://commits.webkit.org/236786@main>

[Chris Dumez]

Oh, what I was reproducing had nothing to do with the GPUProcess and was actually flakily reproducing with the GPUProcess disabled.

I tried on another iPad and I finally have reproduced what I think the bots are experiencing. The GPUProcess exits very shortly after launch due to memory pressure, repeatedly. I think https://commits.webkit.org/236787@main will fix this.

[Chris Dumez]

*** This bug has been marked as a duplicate of bug 224798 ***