1637586 - Terrible performance on https://looping-squares.superhi.com

Status: NEW

(Core :: Graphics: WebRender, defect)

Description

[Jeff Muizelaar [:jrmuizel]]

It looks like we're layerizing a bunch but also invalidating which makes for a really bad time.

Comment 1

[Jeff Muizelaar [:jrmuizel]]

So the reason this is happening is because two.js rounds the transform matrix to 3 decimal places before setting it and we think the scale is constantly changing.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

i.e. FrameLayerBuilder::ChooseScale() is returning alternating 1.0/2.0 as the squares spin. We could make it so we're more likely to round but I wonder if it's worth adding some state so that we make our decision based on the difference from the last scale instead of independently every time.

Comment 3

[Timothy Nikkel (:tnikkel)]

Where would we store the state?

Comment 4

[Jeff Muizelaar [:jrmuizel]]

How about here: https://searchfox.org/mozilla-central/rev/9f074fab9bf905fad62e7cc32faf121195f4ba46/gfx/layers/wr/WebRenderCommandBuilder.cpp#303

Comment 5

[Jeff Muizelaar [:jrmuizel]]

FWIW, upstream fixed/improved the issue: https://github.com/jonobr1/two.js/commit/ff9ade2308da3e28b43c9d8ed1adea79646d9ca8

Comment 6

[Glenn Watson [:gw]]

This is still quite bad - looks like it's all in blob rasterization.