Bobby Holley (:bholley) Reporter
	Description • 7 years ago

STR:

(1) DISABLE_STYLE_SHARING_CACHE=1 STYLO_THREADS=1 ./mach run
(2) start the gecko profiler with 0.2ms resolution
(3) load [1]
(4) paste [2] into the scratchpad and capture a profile.

Profile: http://bit.ly/2tA5k1d

This shows us spending 2ms (~2% of the traversal) in update_animations, which is a lot for a page that doesn't seem to have much in the way of animations going on. I do see centralAuthPPersonalAnimation, but that doesn't sound like something that ought to be very expensive.

Note that this doesn't happen during the initial styling of the document, and is also much more noticeable on this testcase with the style sharing cache disabled.

[1] https://www.dropbox.com/s/zayqjg37wh28v8q/obama-noscript.tar.bz2?dl=0

[2]
var s = document.createElement('style');
s.innerHTML = '*|* { color: red }';
document.head.appendChild(s);
s.remove();
window.getComputedStyle(document.body).color;

	Bobby Holley (:bholley) Reporter
	Comment 1 • 7 years ago

Hiro, any general sense of what's going on here?

	Hiroyuki Ikezoe (:hiro)
	Comment 2 • 7 years ago

At first glance of the profile, nsCSSPseudoElements::GetPseudoType took 0.6ms, it should be replaced by a function just returns ::before, ::after or none (i.e not pseudo).

File bug 1375767 for it.

	Hiroyuki Ikezoe (:hiro)
	Comment 3 • 7 years ago

There is another issue that we call update_animations for the case of FOR_CSS_RULE_CHANGES traversal even if there is no CSS animation.

Filed bug 1375787 for it.

	Bobby Holley (:bholley) Reporter
	Comment 4 • 7 years ago

Thanks for jumping on this Hiro!

	Hiroyuki Ikezoe (:hiro)
	Comment 5 • 7 years ago

Now bug 1375767 and bug 1375787 landed. I don't see update_animations in a profile I got locally.