1493576 - scrolling is not smooth on certain site (uebermedien.de) when WebRender is enabled

Status: VERIFIED WORKSFORME

(Core :: Graphics: WebRender, defect, P4)

Description

[Alice0775 White]

Attachment: about:support

Steps to reproduce:
1. Open URL
2. Scroll down and cache all images if necessary. (to avoid noise such as network and disk activities) 

3. Try scroll
   Mouse wheel
   AutoScroll with middle mouse click
   hold left mouse button down on scroll arrow of scrollbar

Actual Results:
scrolling is not smooth

Expected results:
smooth

Comment 1

[Maire Reavy [:mreavy]]

Are you still seeing a problem?

Comment 2

[Alice0775 White]

(In reply to Maire Reavy [:mreavy] Plz needinfo from comment #1)
> Are you still seeing a problem?


Build ID 	20181010100123
User Agent 	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:64.0) Gecko/20100101 Firefox/64.0

Yes, I can still reproduce if WebRender is enabled.
It quite smooth scrolling if WebRender is disabled.


Steps to reproduce:
1. Open URL
2. Scroll down and cache all images if necessary. (to avoid noise such as network and disk activities) 

3. Try scroll
   Mouse wheel
   AutoScroll with middle mouse click
   hold left mouse button down on scroll arrow of scrollbar

Actual Results:
scrolling is not smooth.
Especially Section of "26 Kommentare " at middle of the page.

Comment 3

[Maire Reavy [:mreavy]]

Jeff -- is this a dup?

Comment 4

[Jeff Muizelaar [:jrmuizel]]

I don't think so. Alice0775 can you get a profile of the problem with Gecko profiler? Please make sure you add "RenderBackend,Renderer,WebRender,Wr" to the list of threads profiled.

Comment 5

[Alice0775 White]

(In reply to Jeff Muizelaar [:jrmuizel] from comment #4)
> I don't think so. Alice0775 can you get a profile of the problem with Gecko
> profiler? Please make sure you add "RenderBackend,Renderer,WebRender,Wr" to
> the list of threads profiled.

https://perfht.ml/2P7tptX

Comment 6

[Jeff Muizelaar [:jrmuizel]]

Thanks. It looks like the problem is just on the "Renderer" thread. Can you get a new profile that only samples that thread?

Comment 7

[Alice0775 White]

(In reply to Jeff Muizelaar [:jrmuizel] from comment #6)
> Thanks. It looks like the problem is just on the "Renderer" thread. Can you
> get a new profile that only samples that thread?

set threads to "Renderer" only, 
https://perfht.ml/2P2V66S

Comment 8

[Jeff Muizelaar [:jrmuizel]]

It looks like this is caused by occasional large chunks of texture upload, this gives us +20ms renderer frames. We should to try track down the cause and see how much is being uploaded.

Comment 9

[Alice0775 White]

No longer reproduce.