Bug 211711 – WinCairo scores 1.00 on MotionMark benchmark since r261113

• Component: Platform
• Status: NEW

[Fujii Hironori]

Since r261113 (Bug 204713), WinCairo scores 1.00 (the worst score) on MotionMark benchmark.

Bug 204713 – Throttling requestAnimationFrame should be controlled by RenderingUpdateScheduler

[Fujii Hironori]

Created attachment 398997 [details]
Patch not to use WM_TIMER

WM_TIMER seems the bottleneck.

[Said Abou-Hallawa]

Is the cause of the MotionMark regression r261113 or r261264 and r261333? I think r261113 was affecting the iOS Low power case only. But after r261264, scheduling the RenderingUpdate on Windows goes through DisplayRefreshMonitor which is different from before.

[Fujii Hironori]

I have a WinCairo bulit binary of r261262. It already has the same issue.
But, I'm not sure which revision is the real culprit.

[Fujii Hironori]

Created attachment 399200 [details]
MotionMark of WinCairo WK1 (r261577)

r261577 fixed another rAF issue of WinCairo WK1, I tried MotionMark with WinCairo WK1.
WinCairo WK1 works well for some tests, but scores 1.00 only for Focus and Images tests.
Those tests are run in Accelerated Compositing mode.

[Fujii Hironori]

WinCairo WK1 AC is using a timer.
https://trac.webkit.org/browser/webkit/trunk/Source/WebKitLegacy/win/WebCoreSupport/AcceleratedCompositingContext.cpp?rev=261577#L274

AppleWin WK1 AC is using PostThreadMessageW.
https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/platform/graphics/ca/win/LayerChangesFlusher.cpp?rev=261577#L119

[Fujii Hironori]

Created attachment 399227 [details]
MotionMark of WinCairo WK1 (r261577) (No updateRendering in WM_PAINT)

Why does WinCairo WK1 non-AC perform well for MotionMark even though it's also using a timer?
The reason seems that it calls Page::updateRendering twice in a single timer fire.
Once in WebView::paint, another in WebView::flushPendingGraphicsLayerChangesSoon.

I tried MotionMark with WinCairo WK1 again by applying a patch not to call Page::updateRendering in WebView::paint.
MotionMark score falled down to 1.39. (I don't know why it isn't 1.00)

diff --git a/Source/WebKitLegacy/win/WebView.cpp b/Source/WebKitLegacy/win/WebView.cpp
index fe7cb6a1d03..ec44027e06c 100644
--- a/Source/WebKitLegacy/win/WebView.cpp
+++ b/Source/WebKitLegacy/win/WebView.cpp
@@ -1285,7 +1285,7 @@ void WebView::paint(HDC dc, LPARAM options)
 {
     LOCAL_GDI_COUNTER(0, __FUNCTION__);
 
-    m_page->updateRendering();
+    //m_page->updateRendering();
 
     if (paintCompositedContentToHDC(dc)) {
         ::ValidateRect(m_viewWindow, nullptr);

[Fujii Hironori]

Created attachment 399240 [details]
html to console.log the interval of requestAnimationFrame

This html shows the duplicated frame of WinCairo WK1 non-AC.

[Fujii Hironori]

Chromium seems to be using own message pump.

[Fujii Hironori]

Created attachment 399295 [details]
experimental patch to conditionally use a timer or callOnMainThread depending on the two-frame-previous tick

FPS can't be stable with this patch.