Oilpan: fix computation of ThreadState::m_collectionRate.

Source/platform/heap/ThreadState.cpp

Index: Source/platform/heap/ThreadState.cpp
diff --git a/Source/platform/heap/ThreadState.cpp b/Source/platform/heap/ThreadState.cpp
index deaa5135d82c09596854b74a0164c6e37fec1fe5..e60da1a227b95c5cdba451b77d3026a890b93cbe 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -893,6 +893,8 @@ void ThreadState::preGC()
     makeConsistentForSweeping();
     prepareRegionTree();
     flushHeapDoesNotContainCacheIfNeeded();
+    if (isMainThread())
+        m_allocatedObjectSizeBeforeSweeping = Heap::allocatedObjectSize() + Heap::markedObjectSize();

[haraken, 2015/01/13 11:56:48]

Shall we rename it to m_objectSizeBeforeGC?

[sof, 2015/01/13 12:11:53]

Done.

 }
 
 void ThreadState::postGC(GCType gcType)
@@ -1037,8 +1039,6 @@ void ThreadState::postGCProcessing()
         return;
 
     m_didV8GCAfterLastGC = false;
-    if (isMainThread())
-        m_allocatedObjectSizeBeforeSweeping = Heap::allocatedObjectSize();

[haraken, 2015/01/13 11:56:48]

Before this CL, m_allocatedObjectSizeBeforeSweeping was 0 in most cases
probably?

[sof, 2015/01/13 12:11:53]

Yes; m_collectionRate then mapping to +Inf.

[haraken, 2015/01/13 12:23:08]

oh...

Also let's add a zero-division check to the calculation of m_collectionRate.

[sof, 2015/01/13 12:35:57]

Asserted on m_collectionRate's range.

 
 #if ENABLE(GC_PROFILE_HEAP)
     // We snapshot the heap prior to sweeping to get numbers for both resources