1742043 - Poor scrolling performance on top10.netflix.com

Status: RESOLVED WORKSFORME

(Core :: Graphics: WebRender, defect)

Description

[Ali]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:95.0) Gecko/20100101 Firefox/95.0

Steps to reproduce:

Visited this page, clicked middle mouse button and moved the mouse up and down in the middle of the page.
https://top10.netflix.com

System specs:
i5 2400
8gb
GTX 970 - 496.13
Win 10 x64

Actual results:

FPS dips down to 20, average GPU usage sits at 50%, can hear coil whine from my GPU.

Expected results:

60 FPS, normal GPU usage, no coil whine.

Comment 1

[Gregory Pappas [:gregp]]

This page seems to use backdrop-filter...a lot. If I add * { backdrop-filter: none !important; } with the style editor, all jank seems to instantly go away.

Comment 2

[Denis Palmeiro [:denispal]]

Hi Ali,

If you are still experiencing this problem, could you please help collect a performance profile to help us investigate further? The instructions on how to collect one are here https://firefox-source-docs.mozilla.org/performance/reporting_a_performance_problem.html

Thank you!

Comment 3

[Ali]

Hi Denis, thanks for the reply. The bug appears to have been resolved with a later version.
I'm no longer experiencing any problems with the page.

Comment 4

[Denis Palmeiro [:denispal]]

Great, thanks!

Comment 5

[Gregory Pappas [:gregp]]

Hi Denis, please reopen this bug. It is once again reproducible because backdrop-filter support was added in the latest Nightly build. Scrolling this page with layout.css.backdrop-filter.enabled to true in a recent Nightly build results in very poor performance.

Comment 6

[Denis Palmeiro [:denispal]]

Thanks for the info. Could you please help capture a performance profile? It would help us diagnose the problem.
The instructions on how to do this are here: https://firefox-source-docs.mozilla.org/performance/reporting_a_performance_problem.html

Comment 7

[Gregory Pappas [:gregp]]

(In reply to Denis Palmeiro [:denispal] from comment #6)

Thanks for the info. Could you please help capture a performance profile? It would help us diagnose the problem.
The instructions on how to do this are here: https://firefox-source-docs.mozilla.org/performance/reporting_a_performance_problem.html

https://share.firefox.dev/3K0VX0k

Comment 8

[Glenn Watson [:gw]]

Looking at the profile, the vast majority of the time is spent in assign_render_pass and assign_free_pass so it's very likely this will be fixed by the patch in https://bugzilla.mozilla.org/show_bug.cgi?id=1765520, which I will push to land shortly.

Comment 9

[Gregory Pappas [:gregp]]

The patch in bug 1765520 did not really fix this. I am still seeing a lot of stuttering when scrolling past areas with heavy use of backdrop-filter.
https://share.firefox.dev/3k8Zq2k
https://share.firefox.dev/3OC0ABM (different profiler settings)

Comment 10

[Glenn Watson [:gw]]

The profiles look like they no longer suffer from the slowness in assign_render_pass, but might be GPU-limited now, or something like that. I'll do some profiling of this page locally this week.

Comment 11

[Gregory Pappas [:gregp]]

Still seeing jank in latest Nightly when scrolling past "Titles in the Global Top 10"
https://share.firefox.dev/3FUv0Lu

Comment 12

[Bob Hood [:bhood]]

Are you still using the old NVIDIA driver (496.13)? Current for your specs is 512.77. Any chance you could update and see how that impacts the behavior?

Comment 13

[Glenn Watson [:gw]]

I checked this on a few local machines and the performance seems good for me with current nightly. Could you try enable gfx.webrender.debug.profiler and gfx.webrender.debug.gpu-time-queries on your machine, and attach a screenshot of the profiler overlay where it is slow on your machine?

Comment 14

[Gregory Pappas [:gregp]]

Attachment: profiler.png

(In reply to Glenn Watson [:gw] from comment #13)

I checked this on a few local machines and the performance seems good for me with current nightly. Could you try enable gfx.webrender.debug.profiler and gfx.webrender.debug.gpu-time-queries on your machine, and attach a screenshot of the profiler overlay where it is slow on your machine?

Comment 15

[Glenn Watson [:gw]]

Thanks. This profile shows a similar result to a couple of other bugs where you've reported bad performance that I was unable to reproduce it. It's very strange.

So what we can see is that the GPU time itself is quite reasonable (certainly under 16ms or better than 60 fps, on almost all frames).

However, we spend a huge amount of CPU time in the renderer thread, which means time spent inside the GPU driver code. If it was blocking in the driver because the GPU couldn't keep up, that would explain it, but that doesn't appear to be the case here. Instead, it looks like we're hitting some other kind of stall or slowness inside the GPU driver, that I have been unable to reproduce so far.

Comment 16

[Ali]

I can no longer repoduce this bug. Performance is now normal with low GPU usage.