Bug 76460

Summary:

Perf improvement via caching Element::styleForRenderer()

Product:

WebKit

Reporter:

Peter Kotwicz <pkotwicz>

Component:

WebCore Misc.

Assignee:

Nobody <webkit-unassigned>

Status:

UNCONFIRMED ---

Severity:

Normal

CC:

jamesr, koivisto, simon.fraser

Priority:

Version:

528+ (Nightly build)

Hardware:

Unspecified

OS:

Unspecified

Attachments:

Description	Flags
test case	none

Description Peter Kotwicz 2012-01-17 08:36:18 PST

styleForRenderer() is a pretty heavy function. In some cases we compute it twice in "Element::recalcStyle" and "NodeRendererFactory::createRendererIfNeeded". NdeRendererFactory is called via Element::attach

I have attached a file where this improvement does improve the performance of Element::recalc. For the attached file, the improvement is on the order of 3-4us. On measurements on a reasonably complex page, doing the caching results in a .1 - .5ms improvement in processing Element::recalc

Comment 1 Antti Koivisto 2012-01-17 10:54:45 PST

I'm planning to get rid of NodeRenderingFactory class which just confuses things. Computing the style twice in case of attach() triggered from recalcStyle is indeed a problem that should be fixed.

Comment 2 Peter Kotwicz 2012-01-17 11:07:20 PST

Created attachment 122784 [details]
test case

Comment 3 Peter Kotwicz 2012-01-17 13:00:51 PST

I did a bit more measurements. For a reasonable web site, for a page where the recalc is done twice, this produces a performance improvement in Element::recalcStyle of about 1%