763120 - Canvas text shadow performance is much worse than Safari on OS X

Status: REOPENED

(Core :: Graphics, defect)

Description

[Jeff Muizelaar [:jrmuizel]]

The following test:
http://jsperf.com/canvas-2d-filltext-performance

Shows us with 1,411, Safari with 17,142 and Chrome with 98,565

One of the big differences with us vs Safari is that Safari uses CoreGraphics ability to shadow any draw operation. Azure currently only does Shadows with a Surface, so we create a temporary surface and shadow that. Technically, this shouldn't be much different in performance but perhaps something is biting us.

Comment 1

[Jeff Muizelaar [:jrmuizel]]

We're getting by the usual CoreGraphics copy-on-write trouble. Safari avoids this and thus gets more performance.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

Attachment: Avoid copy-on-write vm badness

This patch nearly doubles our performance.

Comment 3

[Jeff Muizelaar [:jrmuizel]]

Attachment: Avoid copy-on-write vm badness v2

Comment 4

[Jeff Muizelaar [:jrmuizel]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/06238e6ba3d8

Comment 6

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/06238e6ba3d8

Comment 7

[Jeff Muizelaar [:jrmuizel]]

I'm reopening to leave as a metabug because we're still substantially worse.