1333195 - AccumulateEventRegions has scalability problems

Status: RESOLVED DUPLICATE of bug 1363423

(Core :: Panning and Zooming, defect, P3)

Description

[Jeff Muizelaar [:jrmuizel]]

https://people-mozilla.org/~jmuizelaar/webrender/synthetic/moving-balls.html spends most of it's time in AccumulateEventRegions.

There's a bunch of options for how we can do better.

Comment 1

[Jeff Muizelaar [:jrmuizel]]

If we were to use TiledRegion we'd probably need a version that has different semantics. The current TiledRegion takes the bounds of the rects in a tile. We'd want something that uses the largest contained rectangle.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

I feel like in the default webrender configuration we shouldn't really be doing anything in AccumulateEventRegions, because APZ is off and layout.event-regions.enabled is false by default. So we shouldn't be building event regions at all. Is that not the case?

Comment 3

[Bobby Richter [:secretrobotron]]

Should this run any faster if the window size excludes most of the objects? (e.g. a 300x200 window) It performs just as poor for me, which is unintuitive.

Comment 4

[Jeff Muizelaar [:jrmuizel]]

(In reply to Kartikaya Gupta (email:[e-mail]) from comment #2)
> I feel like in the default webrender configuration we shouldn't really be
> doing anything in AccumulateEventRegions, because APZ is off and
> layout.event-regions.enabled is false by default. So we shouldn't be
> building event regions at all. Is that not the case?

This was profiled in a regular Nightly build without WebRender.

Comment 5

[Kartikaya Gupta (email:[e-mail])]

Ah, ok. I was thrown off by the URL.

Comment 6

[Botond Ballo [:botond]]

The patch in bug 1363423 reduces the paint time of this page from ~2500ms to ~300ms. Forward-duping.