1646859 - High CPU usage using WebRender on Mac and WebRTC

Status: NEW

(Core :: Graphics: WebRender, defect)

Description

[Jessie [:jbonisteel] pls NI]

Drno sees this in a call using whereby.com.

Here are some profiles:

WR on: https://share.firefox.dev/3fhPUWt

WR off: https://share.firefox.dev/2UsEF5m

Comment 1

[Jessie [:jbonisteel] pls NI]

NI-ing Jeff to take a peak at the profiles

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Yeah, so there's something really bad going on in the Renderer thread. It looks like we're spending a lot of time waiting for the GPU.

Nils, how easy it for you to reproduce this? Do you have multiple GPUs in the mac where you see this?

Comment 3

[Nils Ohlmeier [:drno]]

This is trivial to repro for me: I only have to do a WebRTC based 1:1 call on whereby.com while using my external monitor.

And yes my 2018 MBP has:

• Intel UHD Graphics 630
• Radeon Pro 560X

Comment 4

[Nils Ohlmeier [:drno]]

Attachment: about_support.txt

Attaching about:support

Comment 5

[Jeff Muizelaar [:jrmuizel]]

I think this might need bug 1600178 to be fixed. Can you reproduce the problem when not using the external monitor?

Comment 6

[Nils Ohlmeier [:drno]]

Might also be noteworthy that my external monitor is 4K HDR10 and since I'm running 10.15.5 the monitor is running in HDR mode.

Comment 7

[Jeff Muizelaar [:jrmuizel]]

Can you retest this with today's Nightly? 20200708094217 or newer?

Comment 8

[Kris Taeleman (:ktaeleman)]

@Nils: can you check if this is still happening?

Comment 9

[Darkspirit]

(In reply to Nils Ohlmeier [:drno] from comment #6)

@Nils: can you check if this is still happening?

Comment 10

[Nils Ohlmeier [:drno]]

Declaring NI bankruptcy.