1567319 - PayloadPresented is not called for no-op composites

Status: RESOLVED FIXED

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

Description

[Markus Stange [:mstange]]

Sometimes the compositor will detect that nothing changed on the screen and abort the composite. In that case, PayloadPresented will not be called, and payloads will stick around and their latency will be artificially high.

Conceptually, if a key press or a wheel scroll did not change anything in the onscreen rendering, we should count those no-op composites as a success: We have successfully completed the work that needed to be done in response to those events. So I think we should call PayloadPresented even if there is no compositing. The "presented" part is maybe a bit of a lie, then; it's more like "PayloadHandledToCompletion" in reality.

At the moment, for LayerManagerComposite, LayerManagerComposite::Render() is what calls PayloadPresented. No-op composites are detected in its caller, LayerManagerComposite::UpdateAndRender(), so we don't even enter Render() for no-op composites. We should probably move the call to PayloadPresented into LayerManagerComposite::UpdateAndRender().

Comment 1

[Markus Stange [:mstange]]

Alternatively, we could discard all payloads that don't require compositing.

Comment 2

[Markus Stange [:mstange]]

On IRC, Bas agreed that discarding such payloads is probably the right way to go.

Comment 3

[Markus Stange [:mstange]]

Attachment: Bug 1567319 - Discard payloads for no-op composites. r=Bas

Comment 4

[Markus Stange [:mstange]]

This patch fixes LayerManagerComposite. I have not looked at LayerManagerMLGPU or WebRender.
The patch is on top of the patches from bug 1571253.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3851e6be2a2d
Discard payloads for no-op composites. r=bas

Comment 6

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/3851e6be2a2d