Oilpan: adjust GC policy under memory pressure.

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 e4c8669990f7e6c3652fdec1903c184ca9ddc586..9498a2dabdbdc2a2183294d7cf2d97b327c4c86f 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -572,6 +572,20 @@ bool ThreadState::shouldSchedulePreciseGC()
 #endif
 }
 
+namespace {

[haraken, 2015/06/11 04:10:30]

Or static. No strong opinion.

+
+inline bool shouldForceMemoryPressureGC(size_t currentSize, size_t estimatedSize)

[haraken, 2015/06/11 04:10:30]

currentObjectSize, estimatedLiveObjectSize

+{
+    if (currentSize < 300 * 1024 * 1024)
+        return false;
+
+    // If we're consuming too much memory, trigger a conservative GC
+    // aggressively. This is a safe guard to avoid OOM.
+    return (currentSize >> 10) > (estimatedSize >> 10) * 3 / 2;

[haraken, 2015/06/11 04:10:30]

Add a comment about why we want to shift the size.

[sof, 2015/06/11 08:45:02]

Done.

+}
+
+} // namespace
+
 // TODO(haraken): We should improve the GC heuristics.
 // These heuristics affect performance significantly.
 bool ThreadState::shouldForceConservativeGC()
@@ -587,11 +601,8 @@ bool ThreadState::shouldForceConservativeGC()
     // Heap::markedObjectSize() may be underestimated if any thread has not
     // finished completeSweep().
     size_t currentObjectSize = allocatedObjectSize + Heap::markedObjectSize() + WTF::Partitions::totalSizeOfCommittedPages();
-    if (currentObjectSize >= 300 * 1024 * 1024) {
-        // If we're consuming too much memory, trigger a conservative GC
-        // aggressively. This is a safe guard to avoid OOM.
-        return currentObjectSize > estimatedLiveObjectSize * 3 / 2;
-    }
+    if (shouldForceMemoryPressureGC(currentObjectSize, estimatedLiveObjectSize))
+        return true;
     // Schedule a conservative GC if Oilpan has allocated more than 32 MB since
     // the last GC and the current memory usage is >400% larger than
     // the estimated live memory usage.
@@ -792,6 +803,13 @@ void ThreadState::didV8GC()
 {
     checkThread();
     if (isMainThread()) {
+        size_t currentObjectSize = Heap::allocatedObjectSize() + Heap::markedObjectSize() + WTF::Partitions::totalSizeOfCommittedPages();

[haraken, 2015/06/11 04:10:31]

Or you can do:

  if (shouldForceMemoryPressureGC()) {
    Heap::collectGarbage(HeapPointersOnStack, GCWithoutSweep,
Heap::ConservativeGC);
    return;
  }

+        size_t estimatedLiveObjectSize = Heap::estimatedLiveObjectSize();
+        if (shouldForceMemoryPressureGC(currentObjectSize, estimatedLiveObjectSize)) {
+            // Under memory pressure, force a conservative GC.
+            Heap::collectGarbage(HeapPointersOnStack, GCWithoutSweep, Heap::ConservativeGC);
+            return;
+        }
         // Lower the estimated live object size because the V8 major GC is
         // expected to have collected a lot of DOM wrappers and dropped
         // references to their DOM objects.