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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/170536">170536</a></dd>
<dt>Author</dt> <dd>akling@apple.com</dd>
<dt>Date</dt> <dd>2014-06-27 11:06:41 -0700 (Fri, 27 Jun 2014)</dd>
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<h3>Log Message</h3>
<pre>[ARMv7] Skip one particularly expensive fastFree() alignment check.
<https://webkit.org/b/134402>
The size class alignment check in fastFree() was crazy expensive on ARMv7
due to its use of modulo. Disabling it shaves 470ms off of PLT main thread
time in the web process.
Note that this was very hard to identify in profiles due to TCO.
Reviewed by Gavin Barraclough.
* wtf/FastMalloc.cpp:
(WTF::TCMalloc_ThreadCache::CreateCacheIfNecessary):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWTFChangeLog">trunk/Source/WTF/ChangeLog</a></li>
<li><a href="#trunkSourceWTFwtfFastMalloccpp">trunk/Source/WTF/wtf/FastMalloc.cpp</a></li>
</ul>
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<h3>Diff</h3>
<a id="trunkSourceWTFChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WTF/ChangeLog (170535 => 170536)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WTF/ChangeLog 2014-06-27 17:50:36 UTC (rev 170535)
+++ trunk/Source/WTF/ChangeLog 2014-06-27 18:06:41 UTC (rev 170536)
</span><span class="lines">@@ -1,3 +1,19 @@
</span><ins>+2014-06-27 Andreas Kling <akling@apple.com>
+
+ [ARMv7] Skip one particularly expensive fastFree() alignment check.
+ <https://webkit.org/b/134402>
+
+ The size class alignment check in fastFree() was crazy expensive on ARMv7
+ due to its use of modulo. Disabling it shaves 470ms off of PLT main thread
+ time in the web process.
+
+ Note that this was very hard to identify in profiles due to TCO.
+
+ Reviewed by Gavin Barraclough.
+
+ * wtf/FastMalloc.cpp:
+ (WTF::TCMalloc_ThreadCache::CreateCacheIfNecessary):
+
</ins><span class="cx"> 2014-06-26 Andreas Kling <akling@apple.com>
</span><span class="cx">
</span><span class="cx"> Bump FastMalloc thread cache max size to 1MB on iOS.
</span></span></pre></div>
<a id="trunkSourceWTFwtfFastMalloccpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/WTF/wtf/FastMalloc.cpp (170535 => 170536)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WTF/wtf/FastMalloc.cpp 2014-06-27 17:50:36 UTC (rev 170535)
+++ trunk/Source/WTF/wtf/FastMalloc.cpp 2014-06-27 18:06:41 UTC (rev 170536)
</span><span class="lines">@@ -4168,7 +4168,9 @@
</span><span class="cx">
</span><span class="cx"> if (cl) {
</span><span class="cx"> size_t byteSizeForClass = ByteSizeForClass(cl);
</span><ins>+#if !(CPU(ARM_THUMB2) && !CPU(APPLE_ARMV7S))
</ins><span class="cx"> RELEASE_ASSERT(!((reinterpret_cast<char*>(ptr) - reinterpret_cast<char*>(span->start << kPageShift)) % byteSizeForClass));
</span><ins>+#endif
</ins><span class="cx"> pageheap->CacheSizeClass(p, cl);
</span><span class="cx">
</span><span class="cx"> #ifndef NO_TCMALLOC_SAMPLES
</span></span></pre>
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