Title: [113098] trunk/Source/WebCore
- Revision
- 113098
- Author
- [email protected]
- Date
- 2012-04-03 15:39:13 -0700 (Tue, 03 Apr 2012)
Log Message
presentationAttributeCacheMaximumSize is set too low
https://bugs.webkit.org/show_bug.cgi?id=82816
Reviewed by Antti Koivisto.
Performance change, no side effects anticipated.
Prior to r106740, the presentation attribute style cache used to grow unbounded. As part of r110316,
a different version of the cache was introduced with a maximum size of 128. This size gave a 75% hit rate.
However this is bad as the previous cache had a 85% hit rate** and each miss propagate down to the matched
properties cache as we use pointer comparisons.
This change bumps the size to 4096. This size was chosen to bring us back to the previous hit rate while
being a power of 2 (it is the HashMap maximum size). The steep increase is due to the combinational compexity
of the new cache model: we need to match all our attributes' name, value and tag name to get a hit vs
one attribute name, value and a category in the previous cache. To avoid blowing up the memory, we introduced
a timer to clear the cache if the hit rate is too low.
The measured hit rate is actually better now - in the 90% range on most page cyclers. This ups the matched
properties hit rate by 1 percent point on presentation attributes.
** This is not a true apple-to-apple comparison as the cache model was changed.
* dom/StyledElement.cpp:
(PresentationAttributeCacheCleaner):
(WebCore::PresentationAttributeCacheCleaner::PresentationAttributeCacheCleaner):
(WebCore::PresentationAttributeCacheCleaner::didHitPresentationAttributeCache):
(WebCore::PresentationAttributeCacheCleaner::cleanCache):
(WebCore):
(WebCore::presentationAttributeCacheCleaner):
(WebCore::StyledElement::updateAttributeStyle):
Added the logic to clean the presentation attribute cache if we drop below 100 hits per minutes.
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (113097 => 113098)
--- trunk/Source/WebCore/ChangeLog 2012-04-03 22:34:03 UTC (rev 113097)
+++ trunk/Source/WebCore/ChangeLog 2012-04-03 22:39:13 UTC (rev 113098)
@@ -1,3 +1,39 @@
+2012-04-03 Julien Chaffraix <[email protected]>
+
+ presentationAttributeCacheMaximumSize is set too low
+ https://bugs.webkit.org/show_bug.cgi?id=82816
+
+ Reviewed by Antti Koivisto.
+
+ Performance change, no side effects anticipated.
+
+ Prior to r106740, the presentation attribute style cache used to grow unbounded. As part of r110316,
+ a different version of the cache was introduced with a maximum size of 128. This size gave a 75% hit rate.
+
+ However this is bad as the previous cache had a 85% hit rate** and each miss propagate down to the matched
+ properties cache as we use pointer comparisons.
+
+ This change bumps the size to 4096. This size was chosen to bring us back to the previous hit rate while
+ being a power of 2 (it is the HashMap maximum size). The steep increase is due to the combinational compexity
+ of the new cache model: we need to match all our attributes' name, value and tag name to get a hit vs
+ one attribute name, value and a category in the previous cache. To avoid blowing up the memory, we introduced
+ a timer to clear the cache if the hit rate is too low.
+
+ The measured hit rate is actually better now - in the 90% range on most page cyclers. This ups the matched
+ properties hit rate by 1 percent point on presentation attributes.
+
+ ** This is not a true apple-to-apple comparison as the cache model was changed.
+
+ * dom/StyledElement.cpp:
+ (PresentationAttributeCacheCleaner):
+ (WebCore::PresentationAttributeCacheCleaner::PresentationAttributeCacheCleaner):
+ (WebCore::PresentationAttributeCacheCleaner::didHitPresentationAttributeCache):
+ (WebCore::PresentationAttributeCacheCleaner::cleanCache):
+ (WebCore):
+ (WebCore::presentationAttributeCacheCleaner):
+ (WebCore::StyledElement::updateAttributeStyle):
+ Added the logic to clean the presentation attribute cache if we drop below 100 hits per minutes.
+
2012-04-03 Tony Chang <[email protected]>
Implement new flex property and deprecate flex function
Modified: trunk/Source/WebCore/dom/StyledElement.cpp (113097 => 113098)
--- trunk/Source/WebCore/dom/StyledElement.cpp 2012-04-03 22:34:03 UTC (rev 113097)
+++ trunk/Source/WebCore/dom/StyledElement.cpp 2012-04-03 22:39:13 UTC (rev 113098)
@@ -74,6 +74,50 @@
return cache;
}
+class PresentationAttributeCacheCleaner {
+ WTF_MAKE_NONCOPYABLE(PresentationAttributeCacheCleaner);
+public:
+ PresentationAttributeCacheCleaner()
+ : m_cleanTimer(this, &PresentationAttributeCacheCleaner::cleanCache)
+ {
+ }
+
+ void didHitPresentationAttributeCache()
+ {
+ if (presentationAttributeCache().size() < minimumPresentationAttributeCacheSizeForCleaning)
+ return;
+
+ m_hitCount++;
+
+ if (!m_cleanTimer.isActive())
+ m_cleanTimer.startOneShot(presentationAttributeCacheCleanTimeInSeconds);
+ }
+
+private:
+ static const unsigned presentationAttributeCacheCleanTimeInSeconds = 60;
+ static const int minimumPresentationAttributeCacheSizeForCleaning = 100;
+ static const unsigned minimumPresentationAttributeCacheHitCountPerMinute = (100 * presentationAttributeCacheCleanTimeInSeconds) / 60;
+
+ void cleanCache(Timer<PresentationAttributeCacheCleaner>* timer)
+ {
+ ASSERT_UNUSED(timer, timer == &m_cleanTimer);
+ unsigned hitCount = m_hitCount;
+ m_hitCount = 0;
+ if (hitCount > minimumPresentationAttributeCacheHitCountPerMinute)
+ return;
+ presentationAttributeCache().clear();
+ }
+
+ unsigned m_hitCount;
+ Timer<PresentationAttributeCacheCleaner> m_cleanTimer;
+};
+
+static PresentationAttributeCacheCleaner& presentationAttributeCacheCleaner()
+{
+ DEFINE_STATIC_LOCAL(PresentationAttributeCacheCleaner, cleaner, ());
+ return cleaner;
+}
+
void StyledElement::updateStyleAttribute() const
{
ASSERT(!isStyleAttributeValid());
@@ -244,9 +288,10 @@
cacheIterator = presentationAttributeCache().end();
RefPtr<StylePropertySet> style;
- if (cacheHash && cacheIterator->second)
+ if (cacheHash && cacheIterator->second) {
style = cacheIterator->second->value;
- else {
+ presentationAttributeCacheCleaner().didHitPresentationAttributeCache();
+ } else {
style = StylePropertySet::create(isSVGElement() ? SVGAttributeMode : CSSQuirksMode);
unsigned size = attributeCount();
for (unsigned i = 0; i < size; ++i) {
@@ -270,7 +315,7 @@
newEntry->key = cacheKey;
newEntry->value = style.release();
- static const int presentationAttributeCacheMaximumSize = 128;
+ static const int presentationAttributeCacheMaximumSize = 4096;
if (presentationAttributeCache().size() > presentationAttributeCacheMaximumSize) {
// Start building from scratch if the cache ever gets big.
presentationAttributeCache().clear();
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