1616392 - WebRender glitches and flickers on Reddit

Status: RESOLVED FIXED

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

Description

[Virgo]

Attachment: Firefox-Nightly-About-Support.txt

Steps to reproduce:

1. Dual monitor setup (specs below).
2. Open two windows of Firefox Nightly.
3. Move one window to each monitor.
4. Navigate to https://old.reddit.com/r/WormFanfic/ in both windows.
5. Observe a lot of of flickering on the scrolling list of images near the top.

Flickering occurs for me both on Beta (I use 74.0b4 (64-bit) as my daily driver) and brand new clean install of Nightly (75.0a1 (2020-02-18) (64-bit)). Under most circumstances I have only one browser window open on my primary monitor, and I only observe the glitching happen occasionally and randomly while scrolling various webpages. The auto-scrolling image list at https://old.reddit.com/r/WormFanfic/ reproduces the issue reliably during normal usage for me. But the best repro happens with two windows.

System specs:

• OS: Windows 10 (currently build 19568 but I have observed the problem with earlier versions).
• Graphics card: nVidia GeForce RTX 2080 Ti
• Driver version: 442.19
• Multimonitor setup:
  1. Primary: ViewSonic XG2703-GS, connected with DisplayPort cable, 165Hz refresh rate
  2. Secondary: pretty old Asus VG236, connected with DP->DVI adapter and DVI cable, 60Hz refresh rate

My observations:

• Glitching does not seem to occur at all when browser window is on the secondary monitor.
• Glitching occurs occasionally (random flicker every once in a while, maybe once per ten seconds or so) when browser window is on the primary monitor.
• Massive amounts of glitching happen on the primary monitor when I have one browser window open on the primary monitor and one on the secondary monitor, both with https://old.reddit.com/r/WormFanfic/ on the foreground. Browser window on the secondary monitor remains un-glitchy at the same time.

I have captured two videos of the glitch happening.

• Occasional flickers (two at 26th second mark, one at 33rd second mark) with browser open on primary monitor only: https://vardja.eu/Firefox_Nightly_2020-02-18_22-30-54.mp4
• Flickering like there's no tomorrow: browser on primary monitor with another window open on the secondary (secondary not shown, but without glitches): https://vardja.eu/Firefox_Nightly_2020-02-18_22-58-04.mp4

There are no glitches with WebRender disabled.

About:support content attached.

Comment 1

[Jessie [:jbonisteel] pls NI]

Not sure if this is the same glitching issue, but the second video looks especially bad. Glenn do you think grabbing a wr capture here could give us useful info?

Comment 2

[Glenn Watson [:gw]]

Yep, a WR capture here might contain some useful information (unless it's a driver bug that doesn't reproduce in the capture stream on our machines).

Comment 3

[Jessie [:jbonisteel] pls NI]

Virgo, it would be interesting to try and take a WR capture (which can be done in Nightly, currently) and then we can take a look and see if anything interesting shows up there. Here are the steps to do that:

Press Ctrl-Shift-3 when you see the issue. This should generate a wr-capture folder in your AppData\Local windows folder (for example C:\Users\you\AppData\Local\wr-capture). Then please zip and share the contents of that. You can attach it here or email it to me ([e-mail]) This again couuld help us figure out what is going on. Getting a few of those captures could be helpful.'

Thank you!

Comment 4

[Virgo]

Happy to help. I did a few captures and they're all zipped up here: https://vardja.eu/wr-captures-2020-02-19.zip (a bit too large to attach to the bug or send over email, but I hope the download is acceptable).

Annoyingly, when I press ctrl-shift-3 and while the browser is momentarily frozen during the capture, any distortions and artifacts are gone, only to return instantly when the browser becomes responsive again. Because of that, sadly I don't know if there's anything useful in the captures.

Comment 5

[Jessie [:jbonisteel] pls NI]

Glenn - just pinging you so you can take a look and see if these captures tell us anything.

Comment 6

[Glenn Watson [:gw]]

There's nothing obviously wrong in those capture files, from what I can see, and nothing looks wrong when I load them locally (not entirely surprising, given the comment above).

A couple of questions, if you're able to do some testing, which might help us narrow things down:

• Does the glitching still ever occur if
  (1) the secondary monitor is disabled?
  (2) the primary monitor refresh rate is 60 Hz?

• Does setting the gfx.webrender.compositor value in about:config have any effect on the flickering? (a restart of Firefox is required when changing that option).

Comment 7

[Virgo]

Doing more tests in order to answer these questions has provided some interesting new data.

First of all, I am now under the impression that the amount of flickering/glitching on the moving parts of a webpage on the high refresh rate primary monitor is affected by changes happening and things moving on the secondary monitor.

• All windows and gadgets and whatnot closed on the secondary monitor, only pure static desktop wallpaper visible: no flicker on the primary.
• Open a window on the secondary (I used the simplest of simple things - Notepad), maximize, let it stay open in peace: no flicker.
• Type into Notepad, select text, mouse over menus: instant flicker, just add water.

Apparently related to the above discoveries about second screen woes: there was no discernible flicker at any refresh rate when I unplugged the secondary monitor from the graphics card.

Playing around with refresh rates of dual monitor setup under the optimal conditions (lots of movement on the secondary):

• Primary monitor at 60Hz, 85Hz, 100Hz and 120Hz refresh rates: no flicker.
• 144Hz: noticeable flicker.
• 165Hz: strong flicker, more intensive than at 144Hz.

Testing gfx.webrender.compositor under the same conditions (high refresh rate on primary, lots of movement on the secondary):

• Default gfx.webrender.compositor=true: flicker as described.
• Manually set gfx.webrender.compositor=false: no flicker at any point.

Comment 8

[brandon.clinger]

I have been trying to find a place to file this bug. On my Dell XPS 13 with UHD screen and Intel Graphics, WebRender causes the OS to glitch. Not using WebRender or using another browser does not exhibit this symptom. Isolated it to Firefox with WebRender enabled.

See this YouTube video for demonstration.

https://youtu.be/6EL2yonC__s

In General I also experience a general bogged down OS and slower mouse movements with Intel Graphics and WebRender enabled. I cannot articulate this other than WebRender appears to be causing issues with Intel Graphics in general.

Comment 9

[Jessie [:jbonisteel] pls NI]

We have a suspected fix for glitching that is shipping with Firefox 75 (ships this week). Fix is bug 1617083.

This bug does look different than some of the other glitching bugs we have been tracking, so if it is still happening, something different is indeed going on.

brandon.clinger > if you could open a new bug about the slower mouse movements and include the contents of your about:support as a text file that would be useful.

Comment 10

[Virgo]

Apologies for not noticing that this ticket was closed:fixed until the last status update yesterday.

I need to point out that the original issue is not fixed and can still be consistently reproed on my setup. Currently just updated to Firefox 77.0b1 (from beta channel) and was running version 76 shortly before that.

Not sure if this bug report should be reopened, or kept closed and changed to won't fix / can't repro or suchlike.

Thanks.

Comment 11

[Jessie [:jbonisteel] pls NI]

This is probably a different issue than the one we were originally tracking for wr-ui-glitch issues, so I will reopen it.

Comment 12

[Jessie [:jbonisteel] pls NI]

Rares, it would be interesting to see if you can repro anything similar based on the steps provided?

Comment 13

[Rares Doghi, Desktop QA]

Hi, We tried this on 3 different Personal Gaming computers with different setups as you can see in the attached about:Support files with the following monitors and we were unabled to reproduce this issue on our end.

aboutsuppTrevor.txt - Display1 1920x1080@144Hz - Lenovo legion y25f-10 + Display2 1920x1080@60Hz - Samsung
danisupport.txt - Display0 2560x1080@144Hz + Display1 1440x900@60Hz
abouttimi.txt - Display0: 1920x1080@144Hz + Display1: 1920x1080@60Hz + Display2: 1920x1080@59Hz

We tried Fx75 as well as the later versions of Firefox but we still couldnt reproduce the issue on our end.

Comment 14

[Rares Doghi, Desktop QA]

Attachment: aboutsuppTrevor.txt

Comment 15

[Rares Doghi, Desktop QA]

Attachment: danisupport.txt

Comment 16

[Rares Doghi, Desktop QA]

Attachment: abouttimi.txt

Comment 17

[Glenn Watson [:gw]]

I've never been able to repro this locally, so I'm un-assigning for now since there's nothing actionable right now.

Virgo, we do have a couple of other similar bug reports, and we currently suspect this to be a nvidia driver bug that can occur when two monitors are running at different refresh rates. What's the current status of this on your machine?

Comment 18

[Virgo]

Hi Glenn, your assessment seems to correlate with my setup. I can still repro this on my machine. Subjectively the flicker seems less intensive nowadays, but with desktop refresh rate cranked up to 165Hz and WebRender force-enabled (against Firefox's wishes - WEBRENDER_QUALIFIED -> "blocked by env: Monitor refresh rate too high/mixed") it does still happen.

Comment 19

[Glenn Watson [:gw]]

I believe this was resolved by disabling DC in high / mixed refresh rate environments.