1494164 - Incorrect blob painting after scrolling

Status: VERIFIED FIXED

(Core :: Graphics: WebRender, defect, P2)

Description

[Markus Stange [:mstange]]

Attachment: screenshot

STR:
 1. Go to https://static.mozilla.com/moco/en-US/images/mozilla_eoy_2013_EN.svg
 2. Scroll down and back up. Repeat as necessary to reproduce bug.

Expected results:
After scrolling back up, things should look correct.

Actual results:
Every now and then, the top row of tiles has incomplete content after scrolling up. See attached screenshot.

Comment 1

[Markus Stange [:mstange]]

Attachment: other variation

Comment 2

[Jeff Muizelaar [:jrmuizel]]

I suspect this is a regression.

Comment 3

[Darkspirit]

Attachment: 2018-09-27 23-26-49.mp4

mozregression --good 2018-07-16 --bad 2018-07-25 --pref gfx.webrender.all:true -a https://static.mozilla.com/moco/en-US/images/mozilla_eoy_2013_EN.svg
> 34:28.83 INFO: Last good revision: 8984f6868e572079cc991492124ba99747f0f681
> 34:28.83 INFO: First bad revision: 80efe717b563f329a2261a8d23f4ebbc470c432f
> 34:28.83 INFO: Pushlog:
> https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=8984f6868e572079cc991492124ba99747f0f681&tochange=80efe717b563f329a2261a8d23f4ebbc470c432f

> 80efe717b563    Nicolas Silva — Bug 1455422 - Implement the new blob image rasterization hooks. r=kats, gankro
> 7041b2f0aef8    Jeff Muizelaar — Bug 1476636. Update Cargo lockfiles, re-vendor rust dependencies
> 5fdc7f00aba1    Jeff Muizelaar — Bug 1476636. Update webrender to commit 9f21ee5dba0694818a1e2e46d95734ede281447c

Screencast:
first bad (left Nightly icon): One or more tiles(?) are often displayed with a delay or are only shown in part. Scrolling the page causes massive checkerboarding(?), so everything is white at first.

last "good" (right Nightly icon): The page is just scrolling with a huge delay.

Comment 4

[Darkspirit]

Attachment: 2018-09-28 00-20-52.mp4

first bad and last "good" on Win10, GTX1060, at 200% to be able to reproduce

Comment 5

[Sotaro Ikeda [:sotaro]]

I take a look.

Comment 6

[Sotaro Ikeda [:sotaro]]

https://github.com/servo/webrender/pull/3398 in Bug 1492241 addressed the problem for me. The fix will be in m-c soon.

Comment 7

[Sotaro Ikeda [:sotaro]]

(In reply to Sotaro Ikeda [:sotaro] from comment #6)
> https://github.com/servo/webrender/pull/3398 in Bug 1492241 addressed the
> problem for me. The fix will be in m-c soon.

I rechecked the problem. The problem was not addressed. With the patch, it just appeared differently.

Comment 8

[Jeff Muizelaar [:jrmuizel]]

I wonder if this might be caused by the mPaintRect changing.

Comment 9

[Sotaro Ikeda [:sotaro]]

The problem seems to be related to MAX_TILES_PER_REQUEST handling in create_blob_scene_builder_requests().

https://searchfox.org/mozilla-central/source/gfx/wr/webrender/src/resource_cache.rs#1102

If requestd tile size is larger than MAX_TILES_PER_REQUEST, the function just drops drawing of overflowed tiles.

Comment 10

[Sotaro Ikeda [:sotaro]]

MAX_TILES_PER_REQUEST was 64, but the actual request became 286 (11*16) on the STR in comment 0 on my laptop(P50 Win10).

Comment 11

[Sotaro Ikeda [:sotaro]]

(In reply to Sotaro Ikeda [:sotaro] from comment #9)

If requestd tile size is larger than MAX_TILES_PER_REQUEST, the function just drops drawing of overflowed tiles.

If we skip to render some tiles, related rasterized_blob_images and related cached_images nees to be invalidated. Otherwise, obsoleted rendered tiles will be used.

Comment 12

[Sotaro Ikeda [:sotaro]]

Attachment: patch - Clear overflowed blob image tiles

Comment 13

[Sotaro Ikeda [:sotaro]]

Attachment: patch - Clear overflowed blob image tiles

Comment 14

[Sotaro Ikeda [:sotaro]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=65c46c371ec8a1d5efbbd286abc8518fe4a3c4b5

https://treeherder.mozilla.org/perf.html#/compare?originalProject=try&originalRevision=84b74503fbc1ff0ee55edfca287cded4270aae06&newProject=try&newRevision=65c46c371ec8a1d5efbbd286abc8518fe4a3c4b5&framework=1

Comment 15

[Sotaro Ikeda [:sotaro]]

With attachment 9034951 [details] [diff] [review], the problem was addressed for me.

Comment 16

[Sotaro Ikeda [:sotaro]]

Attachment: patch - Clear overflowed blob image tiles

Clean up.

Comment 17

[Sotaro Ikeda [:sotaro]]

Attachment: patch - Clear overflowed blob image tiles

Comment 18

[Sotaro Ikeda [:sotaro]]

I confirmed that the problem was addressed on latest nightly.

Comment 19

[Cristian Baica [:cbaica], Release Desktop QA]

I have managed to reproduce the issue on a macOS 10.14 with Intel Iris Pro using Fx 64.0a1 buildID: 20180925220052.

The issue is verified fixed using Fx 66.0b13 on macOS 10.14, Ubuntu 16.04 and Windows 10 x64. The page is correctly rendered on each scroll-up performed on the page mentioned in comment 0.