Change halfway-to-the-max GC trigger to measure committed pages, not allocated objects

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 5c276e9581c5fa2aac11a33db53cd7dd96a444b5..da6442a02ce4bd34f8902043520f5fbad66af0e0 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -1129,8 +1129,8 @@ class Heap {
   static const int kMaxExecutableSizeHugeMemoryDevice =
       256 * kPointerMultiplier;
 
-  intptr_t OldGenerationAllocationLimit(intptr_t old_gen_size,
-                                        int freed_global_handles);
+  void SetOldGenerationAllocationLimit(intptr_t old_gen_size,
+                                       int freed_global_handles);
 
   // Indicates whether inline bump-pointer allocation has been disabled.
   bool inline_allocation_disabled() { return inline_allocation_disabled_; }
@@ -1244,7 +1244,26 @@ class Heap {
     intptr_t adjusted_allocation_limit =
         old_generation_allocation_limit_ - new_space_.Capacity();
 
-    if (PromotedTotalSize() >= adjusted_allocation_limit) return true;
+    if (PromotedTotalSize() >= adjusted_allocation_limit) {
+      if (FLAG_trace_gc) {
+        PrintF("Next GC will be full: We are at %" V8_PTR_PREFIX

[Hannes Payer (out of office), 2015/03/25 14:30:06]

... likely to be full

[Erik Corry Chromium.org, 2015/03/25 15:16:06]

Done.

+               "dMbytes out of %" V8_PTR_PREFIX "dMbytes\n",
+               PromotedTotalSize() >> 20,
+               old_generation_allocation_limit_ >> 20);
+      }
+      return true;
+    }
+
+    if (CommittedOldGenerationMemory() >=
+        old_generation_committed_memory_limit_) {
+      if (FLAG_trace_gc) {
+        PrintF("Next GC will be full: We are at %" V8_PTR_PREFIX

[Hannes Payer (out of office), 2015/03/25 14:30:06]

... likely to be full

[Erik Corry Chromium.org, 2015/03/25 15:16:06]

Done.

+               "dMbytes committed out of %" V8_PTR_PREFIX "dMbytes\n",
+               CommittedOldGenerationMemory() >> 20,
+               old_generation_committed_memory_limit_ >> 20);
+      }
+      return true;
+    }
 
     return false;
   }
@@ -1635,9 +1654,14 @@ class Heap {
   // Limit that triggers a global GC on the next (normally caused) GC.  This
   // is checked when we have already decided to do a GC to help determine
   // which collector to invoke, before expanding a paged space in the old
-  // generation and on every allocation in large object space.
+  // generation and on every allocation in large object space. This only
+  // measures objects, so it may be underreporting if we have fragmentation.
   intptr_t old_generation_allocation_limit_;
 
+  // As above, but counts pages, not objects, so is more likely to trigger
+  // when we have fragmentation.
+  intptr_t old_generation_committed_memory_limit_;
+
   // Indicates that an allocation has failed in the old generation since the
   // last GC.
   bool old_gen_exhausted_;
@@ -2070,8 +2094,6 @@ class Heap {
       double idle_time_in_ms, size_t size_of_objects,
       size_t mark_compact_speed_in_bytes_per_ms);
 
-  bool WorthActivatingIncrementalMarking();
-
   void ClearObjectStats(bool clear_last_time_stats = false);
 
   inline void UpdateAllocationsHash(HeapObject* object);