Changeset 249232 in webkit

Timestamp:

Aug 28, 2019, 7:24:03 PM (7 years ago)

Author:

Simon Fraser

Message:

PaintFrequencyTracker triggers too many calls to MonotonicTime::now() on layer painting
​https://bugs.webkit.org/show_bug.cgi?id=201261

Reviewed by Zalan Bujtas.

MonotonicTime::now() shows up as expensive when painting layer-heavy content, because PaintFrequencyTracker
makes two calls per layer paint.

Halve the number of calls by storing m_lastPaintTime at the start of the paint; doing so doesn't substantially
change the behavior of the tracker.

• rendering/PaintFrequencyTracker.h:

(WebCore::PaintFrequencyTracker::begin):
(WebCore::PaintFrequencyTracker::end):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• rendering/PaintFrequencyTracker.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-08-28  Simon Fraser  <simon.fraser@apple.com>
+
+        PaintFrequencyTracker triggers too many calls to MonotonicTime::now() on layer painting
+        https://bugs.webkit.org/show_bug.cgi?id=201261
+
+        Reviewed by Zalan Bujtas.
+
+        MonotonicTime::now() shows up as expensive when painting layer-heavy content, because PaintFrequencyTracker
+        makes two calls per layer paint.
+
+        Halve the number of calls by storing m_lastPaintTime at the start of the paint; doing so doesn't substantially
+        change the behavior of the tracker.
+
+        * rendering/PaintFrequencyTracker.h:
+        (WebCore::PaintFrequencyTracker::begin):
+        (WebCore::PaintFrequencyTracker::end):
+
 2019-08-28  Ross Kirsling  <ross.kirsling@sony.com>
 

trunk/Source/WebCore/rendering/PaintFrequencyTracker.h

@@ -62 +62 @@
             m_paintFrequency = PaintFrequency::High;
         }
+
+        m_lastPaintTime = now;
+        ++m_totalPaints;
     }
 
     void end()
     {
-        m_lastPaintTime = MonotonicTime::now();
         ASSERT(m_firstPaintTime);
         ASSERT(m_firstPaintTime <= m_lastPaintTime);
-        ++m_totalPaints;
     }