1408421 - RenderBackend thread does not overlap cpu time with the Render thread

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P1)

Description

[Jeff Muizelaar [:jrmuizel]]

You can see it in this profile of gmail: https://perfht.ml/2kNsK2u

Comment 1

[Jeff Muizelaar [:jrmuizel]]

It looks like this was introduced by 1365196

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Bug 1365196 was added to prevent us from over producing frames. Perhaps the right solution is to only allow one extra frame.

Comment 3

[Peter Chang[:pchang]]

If I changed the maxPendingFrameCount to 2, the scrolling looks better on windows.

[1]http://searchfox.org/mozilla-central/source/gfx/layers/wr/WebRenderBridgeParent.cpp#1144

Comment 4

[Peter Chang[:pchang]]

Actually Bug 1382132 changed the maxPendingFrameCount from 2 to 1. For APZ with WR, it costs time for build_scene because of bug 1408174. I believe we can get benefit from rendering pipeline if we change the maxPendingFrameCount as 2 for scrolling. Sotaro, any thoughts?

Comment 5

[Sotaro Ikeda [:sotaro]]

When maxPendingFrameCount was set to 2, there was cases that frame latency became too big. One example was that render thread always had 2 pending rendering frames. It could happen when rendering take very long. Another example was that background thread thread always had 2 pending frames. It could happen when background thread was too busy. To avoid these situation, I set maxPendingFrameCount to 1. But it restricts too much.

We need to improve the performance by minimizing the latency. Just changing maxPendingFrameCount to 2 could not achieve it.

Comment 6

[Sotaro Ikeda [:sotaro]]

Attachment: patch - Improving throttling GenerateFrame()

Comment 7

[Sotaro Ikeda [:sotaro]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=b33c6143bbf4536f82fbedd0070abbf9329d55ea

Comment 8

[Jeff Muizelaar [:jrmuizel]]

Comment on attachment 8924492 [details] [diff] [review]
patch - Improving throttling GenerateFrame()

Review of attachment 8924492 [details] [diff] [review]:
-----------------------------------------------------------------

::: gfx/webrender_bindings/RenderThread.cpp
@@ +265,5 @@
>    return renderer->Resume();
>  }
>  
> +bool
> +RenderThread::TooMuchPendingFrames(wr::WindowId aWindowId)

TooManyPendingFrames()

Comment 9

[Sotaro Ikeda [:sotaro]]

Attachment: patch - Improving throttling GenerateFrame()

Apply the comment.

Comment 10

[Sotaro Ikeda [:sotaro]]

Attachment: patch - Improving throttling GenerateFrame()

Fixed nits.

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/14a5ae97c682
Improving throttling GenerateFrame() r=jrmuizel

Comment 12

[Narcis Beleuzu [:NarcisB]]

https://hg.mozilla.org/mozilla-central/rev/14a5ae97c682