1670209 - The Firefox browser is shaking when Resized with WebRender on Windows 8.1

Status: RESOLVED WONTFIX

(Core :: Graphics: WebRender, defect)

Description

[Rares Doghi, Desktop QA]

[Affected platforms]:
Platforms: Windows 8.1

[Preconditions]
Reach about:config and set the following pref: gfx.webrender.all = true

[Steps to reproduce]:

1. Launch the Firefox browser and reach reddit.com or 9gag.com
2. From the top try to resize the window down and then go back up.

Expected Result:
The Browser and the content of the web page should not shake.

Actual Results:
When the user resizes the Browser window with WebRender on it each element from the page will start shaking up and down as the user resizes the window.

Please note that I tried to get a screen recording of this issue but the lower frame rate of the recording is making it seem identical with Webrender on and off as well.
GPU used is AMD Radeon HD 6670.

Comment 1

[Rares Doghi, Desktop QA]

The Severity for this issue should be an S3.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Do you see something similar in Chrome?

Comment 3

[Jeff Muizelaar [:jrmuizel]]

Also can you post the contents of about:support?

Comment 4

[Rares Doghi, Desktop QA]

Attachment: aboutSuppwin8.txt

I have attached the about support from this pc, also on Chrome this issue does not occur at all.

Comment 5

[Darkspirit]

Can this be fixed by disabling layout.css.scroll-anchoring.enabled? If yes, then it's related to bug 1541072.

Comment 6

[Rares Doghi, Desktop QA]

A few things here, I tested this issue in our latest Beta and Nightly builds and the issue is a lot less noticeable in Beta while in our latest Nightly build even less, only comparing to chrome you can spot any difference.

I tried disabling layout.css.scroll-anchoring.enabled in beta where I could reproduce the issue a little better but I don't see any differences with it on or off.

Comment 7

[Matt Woodrow (:mattwoodrow)]

Sotaro, can you reproduce this? Seems like it might be similar to other resizing race issues we've had in the past.

Comment 8

[Sotaro Ikeda [:sotaro]]

In the past, we noticed 4 causes of windows resizing on Windows. [3] or [4] might be related to this case.

• [1] Use Compositor Window in GPU process.
  • Compositor window was created only when DirectComposition(only on windows 10).
    It should not affect to Windows8, since it is created only when WebRender uses DirectComposition in GPU process.
• [2] Use DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL at SwapChain.
  • DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL is not used on Windows 8.
    https://searchfox.org/mozilla-central/rev/7b07725fe9dc5d59a525990fc1dba78bc8b82af1/gfx/thebes/gfxPlatform.cpp#2782
  • On Window 10 with DirectComposition, gecko does not use DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL SwapChain anymore.
    Instead, uses DCompositionVirtualSurface, it reduced resizing problem on Windows10.
• [3] WebRender rendering happen on RenderThread and multiple WebRendering tasks were queued during resizing.
• [4] WebRenderLayerManager::FlushRendering() does not work as sync when it is necessary.

Bug 1579732 has links to another resizing bugs.

Comment 9

[Sotaro Ikeda [:sotaro]]

I do not have Windows8.1 PC. But I have 2 Windows 7 PCs. The shaking did not happen on one PC, but it happened on another PC. But the shake happened even without WebRender(CompositorD3D11). On the PC, I did not see the shaking with chrome browser.

Comment 10

[Jeff Muizelaar [:jrmuizel]]

Rares, remind me, do you have other hardware that has 8.1? Does the problem happen on that hardware?

Comment 11

[Rares Doghi, Desktop QA]

Yes Jeff, this issue also occured on an Intel HD 530 but not as visible as on the one with that AMD Radeon HD 6670, I will attach the about support from that machine.

Comment 12

[Rares Doghi, Desktop QA]

Attachment: aboutsupportintl.txt

Comment 13

[Jeff Muizelaar [:jrmuizel]]

Rares, can you make a video with a cell phone video of it? And confirm that it only happens with WebRender?

Comment 14

[Rares Doghi, Desktop QA]

Hi Jeff, Im definitely seeing this issue with WebRender off as well just not that strong, I hope you can see something from the following links but I'm not sure if google Drive will take some of the quality, I have also tried to film it in slow motion not sure if you can spot any differences but on the left side we have WebRender ON and on the right side WebRender off.

https://drive.google.com/file/d/1_ykmDyQYfSESWggIlgH_OCUl6GnWNep8/view?usp=sharing

https://drive.google.com/file/d/1i4txeNByknF_mJtnwxvIiyWxSCI9WsIX/view?usp=sharing

Comment 15

[Jeff Muizelaar [:jrmuizel]]

(In reply to Rares Doghi from comment #14)

Hi Jeff, Im definitely seeing this issue with WebRender off as well just not that strong, I hope you can see something from the following links but I'm not sure if google Drive will take some of the quality, I have also tried to film it in slow motion not sure if you can spot any differences but on the left side we have WebRender ON and on the right side WebRender off.

https://drive.google.com/file/d/1_ykmDyQYfSESWggIlgH_OCUl6GnWNep8/view?usp=sharing

https://drive.google.com/file/d/1i4txeNByknF_mJtnwxvIiyWxSCI9WsIX/view?usp=sharing

Is there a particular part of the browser I should look at to see it?

Comment 16

[Rares Doghi, Desktop QA]

Yes the titles like : "What is your favorite dead video game franchise" as well as the images from the page when I am resizing the left window you can see that they all go down a bit and then jump up , it happens on the right window as well just not as noticeable.

On the slow motion video : https://drive.google.com/file/d/1i4txeNByknF_mJtnwxvIiyWxSCI9WsIX/view?usp=sharing you can see this a little better.

Comment 17

[Sotaro Ikeda [:sotaro]]

Windows 8.1 is not supported now.