Bug 219445 - Changing transforms on layer-backed elements with large subtrees can be incredibly slow
Summary: Changing transforms on layer-backed elements with large subtrees can be incre...
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Compositing (show other bugs)
Version: Safari 13
Hardware: All All
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2020-12-02 11:17 PST by Jan Van Boghout
Modified: 2020-12-07 16:37 PST (History)
6 users (show)

See Also:

Attachments
Reproduction and details (5.28 KB, text/html)
2020-12-02 11:17 PST, Jan Van Boghout 		no flags Details
test case that isn't so slow as to be unusable (5.28 KB, text/html)
2020-12-07 16:37 PST, Simon Fraser (smfr) 		no flags Details
View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Jan Van Boghout 2020-12-02 11:17:17 PST 
Created attachment 415238 [details]
Reproduction and details

Open the attached reproduction file and note the instructions. When profiling, you'll note heavy activity in "Styles Recalculated".

Expected:
Changing a transform on a layer-backed element after it has laid out and painted is independent of the complexity of the subtree.

Actual:
There's a huge performance difference, implying the subtree is getting dirtied for no reason.
Comment 1 Smoley 2020-12-07 10:54:34 PST 
Thanks for filing, I can reproduce this on Safari 13.1.3 as well as TOT 14.1
Comment 2 Radar WebKit Bug Importer 2020-12-07 10:54:44 PST 
<rdar://problem/72054623>
Comment 3 Simon Fraser (smfr) 2020-12-07 11:01:11 PST 
Not quite sure what's going on in the testcase, but sampling shows it spending a lot of time in:

    +                             2724 WebCore::Document::resolveStyle(WebCore::Document::ResolveStyleType)  (in WebCore) + 1243  [0x7fff3abe28db]
    +                               2724 WebCore::Document::updateRenderTree(std::__1::unique_ptr<WebCore::Style::Update const, std::__1::default_delete<WebCore::Style::Update const> >)  (in WebCore) + 180  [0x7fff3abe23a4]
    +                                 2724 WebCore::RenderTreeUpdater::commit(std::__1::unique_ptr<WebCore::Style::Update const, std::__1::default_delete<WebCore::Style::Update const> >)  (in WebCore) + 2388  [0x7fff3b67f774]
    +                                   2724 WebCore::RenderTreeUpdater::updateElementRenderer(WebCore::Element&, WebCore::Style::ElementUpdate const&)  (in WebCore) + 87  [0x7fff3b680d57]
    +                                     2723 WebCore::RenderTreeUpdater::tearDownRenderers(WebCore::Element&, WebCore::RenderTreeUpdater::TeardownType, WebCore::RenderTreeBuilder&)  (in WebCore) + 491  [0x7fff3b68267b]
    +                                     ! 2721 WebCore::RenderTreeUpdater::tearDownRenderers(WebCore::Element&, WebCore::RenderTreeUpdater::TeardownType, WebCore::RenderTreeBuilder&)::$_2::operator()(unsigned int) const  (in WebCore) + 787  [0x7fff3b682d13]
    +                                     ! : 2706 WebCore::RenderTreeBuilder::destroyAndCleanUpAnonymousWrappers(WebCore::RenderObject&)  (in WebCore) + 286  [0x7fff3b6732be]
    +                                     ! : | 2706 WebCore::RenderTreeBuilder::removeAnonymousWrappersForInlineChildrenIfNeeded(WebCore::RenderElement&)  (in WebCore) + 593,128,...  [0x7fff3b672f31,0x7fff3b672d60,...]
Comment 4 Simon Fraser (smfr) 2020-12-07 16:37:33 PST 
Created attachment 415600 [details]
test case that isn't so slow as to be unusable