Add a UseCounter that measures the amount of memory used in PartitionAlloc

Source/wtf/Partitions.cpp

Index: Source/wtf/Partitions.cpp
diff --git a/Source/wtf/Partitions.cpp b/Source/wtf/Partitions.cpp
index 800632ea4a009c43f26dd95ac4e1a18aab0a100b..7f3422d98a4070fe4bddb5f69659fd2d1e176e3a 100644
--- a/Source/wtf/Partitions.cpp
+++ b/Source/wtf/Partitions.cpp
@@ -42,8 +42,9 @@ PartitionAllocatorGeneric Partitions::m_fastMallocAllocator;
 PartitionAllocatorGeneric Partitions::m_bufferAllocator;
 SizeSpecificPartitionAllocator<3328> Partitions::m_objectModelAllocator;
 SizeSpecificPartitionAllocator<1024> Partitions::m_renderingAllocator;
+HistogramEnumerationFunction Partitions::m_histogramEnumeration = nullptr;
 
-void Partitions::initialize()
+void Partitions::initialize(HistogramEnumerationFunction histogramEnumeration)
 {
     static int lock = 0;
     // Guard against two threads hitting here in parallel.
@@ -53,6 +54,7 @@ void Partitions::initialize()
         m_bufferAllocator.init();
         m_objectModelAllocator.init();
         m_renderingAllocator.init();
+        m_histogramEnumeration = histogramEnumeration;
         s_initialized = true;
     }
     spinLockUnlock(&lock);
@@ -69,4 +71,21 @@ void Partitions::shutdown()
     (void) m_fastMallocAllocator.shutdown();
 }
 
+void Partitions::recordMemoryUsageIfNeeded()

[Chris Evans, 2015/04/02 15:53:01]

This might be called on any thread -- is that OK? Probably worth at least a
comment.

It won't be called concurrently because of the existing locking. We should
probably document (and preserve) that invariant too, possibly in
PartitionAlloc.h, if you accept my other comment about making callback
registration explicit?

[haraken, 2015/04/02 23:31:32]

To avoid races on the static variable, I restricted it to the main thread.

+{
+    static const size_t maxSizeInMB = 4 * 1024;
+    static bool s_isUsedSlot[maxSizeInMB] = { false };

[Chris Evans, 2015/04/02 15:53:01]

This is kind of big -- 4KB. If we keep it, I recommend storing the booleans as
single bits.

+
+    if (!m_histogramEnumeration)
+        return;
+    size_t sizeInMB = Partitions::totalSizeOfCommittedPages() / 1024 / 1024;
+    if (sizeInMB >= maxSizeInMB)
+        sizeInMB = maxSizeInMB - 1;
+    if (!s_isUsedSlot[sizeInMB]) {
+        // Send the UseCounter only once for each slot for each renderer process.

[Chris Evans, 2015/04/02 15:53:01]

Another strategy -- which would eliminate the above array altogether -- would be
to only send the UseCounter when we see a new record high?

[haraken, 2015/04/02 23:31:32]

Nice idea! Done.

+        m_histogramEnumeration("PartitionAlloc.CommittedSize", sizeInMB, maxSizeInMB);
+        s_isUsedSlot[sizeInMB] = true;
+    }
+}
+
 } // namespace WTF