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Issue 161289: Some sites, e.g. techcrunch.com, theverge.com, fall into slow scroll path
8 people starred this issue and may be notified of changes. Back to list
 
Project Member Reported by klobag@chromium.org, Nov 15, 2012
Version: ToT
OS: Android

What steps will reproduce the problem?
1. Load techcrunch.com or theverge.com in Chrome for Android (desktop site)
2. Scroll the page down

What is the expected output? What do you see instead?
Expected: page scroll smoothly while we may see white background.
Observed: page scroll janky, never see white background

Please use labels and text to provide additional information.
If you use trace, you will see we are scrolling from the webkit instead of impl thread.

Chrome for Android sets switches::kEnableCompositingForFixedPosition flag in its content_startup_flags.cc.

Need investigation on why we fall into the slow path.
Nov 15, 2012
#1 skyos...@chromium.org
The first thing to do is to take a trace and check what reason is logged for slow scrolling in LayerTreeHostImpl::scrollBegin(). We might also want to add a trace for ScrollingCoordinator::mainThreadScrollingReasons(). I also see there's been some recent changes to the triggers for slow path scrolling, e.g., https://bugs.webkit.org/show_bug.cgi?id=101303.
Nov 15, 2012
#2 tomhudson@chromium.org
(No comment was entered for this change.)
Cc: tomhudson@chromium.org
Nov 15, 2012
#3 wiltz...@chromium.org
(No comment was entered for this change.)
Labels: Hotlist-AndroidGraphics
Nov 16, 2012
#4 wangxianzhu@chromium.org
Yes, https://bugs.webkit.org/show_bug.cgi?id=101303 is the reason for slow scrolling. ScrollingCoordinator::mainThreadScrollingReasons() is HasNonLayerFixedObjects because there is an out-of-view fixed element not composited. Actually we need the element (whose z-index is negative) not composited because otherwise it will cause several full screen layers and hundreds of small layers. Perhaps we can totally hide that fixed element because it is never visible, so that we can avoid HasNonLayerFixedObjects.
Nov 16, 2012
#5 wangxianzhu@chromium.org
(No comment was entered for this change.)
Labels: WebKit-ID-101303
Nov 16, 2012
#6 bugdro...@chromium.org
https://bugs.webkit.org/show_bug.cgi?id=101303
Labels: -WebKit-ID-101303 WebKit-ID-101303-RESOLVED
Nov 16, 2012
#7 wangxianzhu@chromium.org
Sorry, I misread the status of https://bugs.webkit.org/show_bug.cgi?id=101303. It is supposed to resolve the issue. Looking into the reason of HasNonLayerFixedObjects.
Nov 16, 2012
#8 wangxianzhu@chromium.org
(No comment was entered for this change.)
Labels: -WebKit-ID-101303-RESOLVED WebKit-ID-102543
Nov 16, 2012
#9 bugdro...@chromium.org
https://bugs.webkit.org/show_bug.cgi?id=102543
Labels: -WebKit-ID-102543 WebKit-ID-102543-NEW
Nov 20, 2012
#10 wangxianzhu@chromium.org
The patch to 102543 resolve the issue that out-of-view fixed positioned elements cause slow scrolling.

However, with the patch theverge.com still uses the slow scrolling path. With the patch LayerImpl::shouldScrollOnMainThread() is false, but tryScroll() returns ScrollOnMainThread because the page has wheel event handlers.  Bug 160715  addresses this issue.
Blockedon: chromium:160715
Nov 27, 2012
#12 wangxianzhu@chromium.org
The patch to webkit.org/b/102543 is still under review.
Status: Started
Dec 3, 2012
#13 wangxianzhu@chromium.org
 Issue 163782  has been merged into this issue.
Cc: leviw@chromium.org peter@chromium.org ael...@chromium.org
Dec 10, 2012
#15 srika...@chromium.org
(No comment was entered for this change.)
Labels: OS-Android
Dec 10, 2012
#16 bugdro...@chromium.org
https://bugs.webkit.org/show_bug.cgi?id=102543
Labels: -WebKit-ID-102543-NEW WebKit-ID-102543-ASSIGNED
Dec 11, 2012
#17 vino...@chromium.org
(No comment was entered for this change.)
Labels: ReleaseBlock-Dev
Dec 11, 2012
#18 vino...@chromium.org
(No comment was entered for this change.)
Labels: -ReleaseBlock-Beta
Dec 11, 2012
#20 bugdro...@chromium.org
http://trac.webkit.org/changeset/137399
Labels: WebKit-Rev-137399
Dec 11, 2012
#21 bugdro...@chromium.org
https://bugs.webkit.org/show_bug.cgi?id=102543
http://trac.webkit.org/changeset/137409
Labels: -WebKit-ID-102543-ASSIGNED WebKit-ID-102543-RESOLVED WebKit-Rev-137409
Dec 13, 2012
#22 wangxianzhu@chromium.org
(No comment was entered for this change.)
Status: Fixed
Mar 10, 2013
#23 bugdro...@chromium.org
(No comment was entered for this change.)
Labels: -Area-WebKit -Mstone-25 Cr-Content M-25
Apr 5, 2013
#24 bugdro...@chromium.org
(No comment was entered for this change.)
Labels: -Cr-Content Cr-Blink
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