1694017 - [NSFW] Scrolling on a NSFW reddit page is bad with the Reddit New Design, and the "Safe browsing mode" enabled

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect)

Description

[Mayank Bansal]

STR:
0: Enable SW-WR

1. Set the new design of Reddit as default
2. Enable the "Safe Browsing Mode" on Reddit. (On reddit, click on the username on top right->User Settings->Feed Settings->Safe Browsing Mode-> Enable)
3. Go to a NSFW page like this : https://www.reddit.com/user/eat_a_p3ach/
   3.5 Optional : Wait for 1 minute to let the GC/CC do its thing
4. Put the mouse cursor on one of the images/videos of the feed, an start scrolling down.

ER: Smooth scrolling
AR: Choppy scrolling

"Safe Browsing" on : https://share.firefox.dev/3ulDvZC
"Safe Browsing" off : https://share.firefox.dev/3bowH54

Comment 1

[Mayank Bansal]

I have filed this separately from bug 1685848 as the difference in performance with SWWR is much more stark compared to HWWR.

Comment 2

[Mayank Bansal]

Attachment: about:support with sw-wr force enabled

Comment 3

[Lee Salzman [:lsalzman]]

The time looks like it is spent most in brush_blend, brush_image_ADVANCED_BLEND, and cs_scale_TEXTURE_2D (apparently doing a downscale in blendTextureLinearFallback?).

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Attachment: Artifact in blurred area

In addition to the bad performance I also see artifacting in the blurred area.

Comment 5

[Jeff Muizelaar [:jrmuizel]]

Turning off the two blur filters makes a big difference.
Before: https://share.firefox.dev/3aDOsho
After: https://share.firefox.dev/37C0lm5

The way the blurring is implemented is very weird. It seems like there are two <img> each of which point at an image that has been blurred on the server side and then further blurred on the client side. The bottom image has filter: blur(20px) brightness(.8); and the top image has filter: blur(60px);

Comment 6

[Jeff Muizelaar [:jrmuizel]]

Attachment: Standalone test case (scroll down to see content)

Comment 7

[Jeff Muizelaar [:jrmuizel]]

I actually see the artifacts with hardware webrender too.

Comment 8

[Lee Salzman [:lsalzman]]

Attachment: Bug 1694017 - Accelerate 2x downscaling in SWGL. r?jrmuizel

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/ae5b26d89bf1
Accelerate 2x downscaling in SWGL. r=jrmuizel

Comment 10

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/ae5b26d89bf1

Comment 11

[Lee Salzman [:lsalzman]]

Comment on attachment 9205164 [details]
Bug 1694017 - Accelerate 2x downscaling in SWGL. r?jrmuizel

Beta/Release Uplift Approval Request

• User impact if declined: Trying to do partial SW-WR rollout on Linux. Would like to avoid people reporting significant performance regressions months down the line. This will avoid slowdowns in sites that use blur filters.
• Is this code covered by automated tests?: Yes
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): Only impacts SW-WR/Linux. We can abort the rollout if unstable. Adequate time to deal with any bugs.
• String changes made/needed:

Comment 12

[Ryan VanderMeulen [:RyanVM]]

Comment on attachment 9205164 [details]
Bug 1694017 - Accelerate 2x downscaling in SWGL. r?jrmuizel

Approved for 87.0b4.

Comment 13

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/921b06820cc4