Mark faster when executing write barriers.

src/incremental-marking.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 82 matching lines @@
 
   void MarkingComplete(CompletionAction action);
 
   // It's hard to know how much work the incremental marker should do to make
   // progress in the face of the mutator creating new work for it.  We start
   // of at a moderate rate of work and gradually increase the speed of the
   // incremental marker until it completes.
   // Do some marking every time this much memory has been allocated or that many
   // heavy (color-checking) write barriers have been invoked.
   static const intptr_t kAllocatedThreshold = 65536;
-  static const intptr_t kWriteBarriersInvokedThreshold = 65536;
+  static const intptr_t kWriteBarriersInvokedThreshold = 32768;
   // Start off by marking this many times more memory than has been allocated.
   static const intptr_t kInitialMarkingSpeed = 1;
   // But if we are promoting a lot of data we need to mark faster to keep up
   // with the data that is entering the old space through promotion.
   static const intptr_t kFastMarking = 3;
   // After this many steps we increase the marking/allocating factor.
   static const intptr_t kMarkingSpeedAccellerationInterval = 1024;
   // This is how much we increase the marking/allocating factor by.
   static const intptr_t kMarkingSpeedAccelleration = 2;
   static const intptr_t kMaxMarkingSpeed = 1000;
@@ skipping 165 matching lines @@
   int no_marking_scope_depth_;
 
   int unscanned_bytes_of_large_object_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_INCREMENTAL_MARKING_H_