Revert of Remove redundant activation threshold for incremental marking.

src/heap/incremental-marking.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/incremental-marking.h"
 
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
 #include "src/conversions.h"
 #include "src/heap/gc-idle-time-handler.h"
@@ skipping 456 matching lines @@
   return CanBeActivated() &&
          heap_->HeapIsFullEnoughToStartIncrementalMarking(
              heap_->old_generation_allocation_limit());
 }
 
 
 bool IncrementalMarking::WasActivated() { return was_activated_; }
 
 
 bool IncrementalMarking::CanBeActivated() {
+#ifndef DEBUG
+  static const intptr_t kActivationThreshold = 8 * MB;
+#else
+  // TODO(gc) consider setting this to some low level so that some
+  // debug tests run with incremental marking and some without.
+  static const intptr_t kActivationThreshold = 0;
+#endif
   // Only start incremental marking in a safe state: 1) when incremental
   // marking is turned on, 2) when we are currently not in a GC, and
   // 3) when we are currently not serializing or deserializing the heap.
   // Don't switch on for very small heaps.
   return FLAG_incremental_marking && heap_->gc_state() == Heap::NOT_IN_GC &&
          heap_->deserialization_complete() &&
-         !heap_->isolate()->serializer_enabled();
+         !heap_->isolate()->serializer_enabled() &&
+         heap_->PromotedSpaceSizeOfObjects() > kActivationThreshold;
 }
 
 
 void IncrementalMarking::ActivateGeneratedStub(Code* stub) {
   DCHECK(RecordWriteStub::GetMode(stub) == RecordWriteStub::STORE_BUFFER_ONLY);
 
   if (!IsMarking()) {
     // Initially stub is generated in STORE_BUFFER_ONLY mode thus
     // we don't need to do anything if incremental marking is
     // not active.
@@ skipping 652 matching lines @@
 void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
   idle_marking_delay_counter_++;
 }
 
 
 void IncrementalMarking::ClearIdleMarkingDelayCounter() {
   idle_marking_delay_counter_ = 0;
 }
 }  // namespace internal
 }  // namespace v8