Oilpan: Schedule a precise GC when a page navigates

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 f751bba454a88eeb6e42e80aaae8a002596dcfe4..99f72401c13e3becef994587052d23267affd5d3 100644
--- a/Source/platform/heap/ThreadState.cpp
+++ b/Source/platform/heap/ThreadState.cpp
@@ -650,6 +650,24 @@ bool ThreadState::shouldSchedulePreciseGC()
 #endif
 }
 
+void ThreadState::schedulePageNavigationGCIfNeeded(float estimatedRemovalRatio)
+{

[haraken, 2015/08/06 07:52:43]

Add:

  if (UNLIKELY(isGCForbidden()))
    return false;

  if (shouldForceMemoryPressureGC())
    return true;

[keishi, 2015/08/11 06:59:53]

Done.

+    // Avoid potential overflow by truncating to Kb.
+    size_t allocatedObjectSizeKb = Heap::allocatedObjectSize() >> 10;
+    // The estimated size is updated when the main thread finishes lazy
+    // sweeping. If this thread reaches here before the main thread finishes
+    // lazy sweeping, the thread will use the estimated size of the last GC.
+    size_t estimatedLiveObjectSizeKb = (estimatedLiveObjectSize() >> 10) * (1 - estimatedRemovalRatio);
+    // Heap::markedObjectSize() may be underestimated if any thread has not
+    // finished completeSweep().
+    size_t currentObjectSizeKb = currentObjectSize() >> 10;
+    // Schedule a precise GC if Oilpan has allocated more than 1 MB since
+    // the last GC and the current memory usage is >50% larger than
+    // the estimated live memory usage.
+    if (allocatedObjectSizeKb >= 1024 && currentObjectSizeKb > (estimatedLiveObjectSizeKb * 3) / 2)
+        schedulePreciseGC();
+}

[haraken, 2015/08/06 07:52:42]

bool ThreadState::shouldSchedulePageNavigationGC(float estimatedRemovalRatio)
{
  ...;
}

void ThreadState::schedulePageNavigationGCIfNeeded(float estimatedRemovalRatio)
{
  ASSERT(checkThread());
  // Finish on-going lazy sweeping.
  completeSweep();   <--- I think it makes sense to do this.
  ASSERT(!isSweepingInProgress());
  ASSERT(!sweepForbidden());

  Heap::reportMemoryUsageForTracing();
  if (shouldSchedulePageNavigationGC(estimatedRemovalRatio))
    schedulePageNavigationGC();
}

void ThreadState::schedulePageNavigationGC()
{
  ASSERT(checkThread());
  ASSERT(!isSweepingInProgress());
  setGCState(PageNavigationGCScheduled);
}

[keishi, 2015/08/11 06:59:53]

Done.

+
 // TODO(haraken): We should improve the GC heuristics.
 // These heuristics affect performance significantly.
 bool ThreadState::shouldForceConservativeGC()
@@ -908,7 +926,7 @@ void ThreadState::runScheduledGC(StackState stackState)
         Heap::collectAllGarbage();
         break;
     case PreciseGCScheduled:
-        Heap::collectGarbage(NoHeapPointersOnStack, GCWithoutSweep, Heap::PreciseGC);
+        Heap::collectGarbage(NoHeapPointersOnStack, GCWithSweep, Heap::PreciseGC);

[haraken, 2015/08/06 07:52:43]

Hmm, I'm fine with forcing sweeping for navigation GCs but want to avoid forcing
sweeping for non-navigation GCs. Can we introduce a new state
"PageNavigationGCScheduled"?

[keishi, 2015/08/11 06:59:53]

Done.

         break;
     case IdleGCScheduled:
         // Idle time GC will be scheduled by Blink Scheduler.