Start incremental marking on idle notification.

src/heap.h

 // Copyright 2011 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 1250 matching lines @@
   intptr_t OldGenAllocationLimit(intptr_t old_gen_size) {
     const int divisor = FLAG_stress_compaction ? 8 : 2;
     intptr_t limit =
         Max(old_gen_size + old_gen_size / divisor, kMinimumAllocationLimit);
     limit += new_space_.Capacity();
     limit *= old_gen_limit_factor_;
     intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
     return Min(limit, halfway_to_the_max);
   }
 
-  // Can be called when the embedding application is idle.
-  bool IdleNotification();
+  // Implements the corresponding V8 API function.
+  bool IdleNotification(int hint);
 
   // Declare all the root indices.
   enum RootListIndex {
 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex,
     STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION)
 #undef ROOT_INDEX_DECLARATION
 
 // Utility type maps
 #define DECLARE_STRUCT_MAP(NAME, Name, name) k##Name##MapRootIndex,
   STRUCT_LIST(DECLARE_STRUCT_MAP)
@@ skipping 102 matching lines @@
   }
 
   Marking* marking() {
     return &marking_;
   }
 
   IncrementalMarking* incremental_marking() {
     return &incremental_marking_;
   }
 
+  bool IsSweepingComplete() {
+    return old_data_space()->IsSweepingComplete() &&
+           old_pointer_space()->IsSweepingComplete();
+  }
+
+  bool AdvanceSweepers(int step_size) {
+    bool sweeping_complete = old_data_space()->AdvanceSweeper(step_size);
+    sweeping_complete &= old_pointer_space()->AdvanceSweeper(step_size);
+    return sweeping_complete;
+  }
+
   ExternalStringTable* external_string_table() {
     return &external_string_table_;
   }
 
   // Returns the current sweep generation.
   int sweep_generation() {
     return sweep_generation_;
   }
 
   inline Isolate* isolate();
@@ skipping 15 matching lines @@
   void QueueMemoryChunkForFree(MemoryChunk* chunk);
   void FreeQueuedChunks();
 
   // Completely clear the Instanceof cache (to stop it keeping objects alive
   // around a GC).
   inline void CompletelyClearInstanceofCache();
 
   // The roots that have an index less than this are always in old space.
   static const int kOldSpaceRoots = 0x20;
 
+  bool idle_notification_will_schedule_next_gc() {
+    return idle_notification_will_schedule_next_gc_;
+  }
+
  private:
   Heap();
 
   // This can be calculated directly from a pointer to the heap; however, it is
   // more expedient to get at the isolate directly from within Heap methods.
   Isolate* isolate_;
 
   intptr_t code_range_size_;
   int reserved_semispace_size_;
   int max_semispace_size_;
@@ skipping 305 matching lines @@
   bool IsIncreasingSurvivalTrend() {
     return survival_rate_trend() == INCREASING;
   }
 
   bool IsHighSurvivalRate() {
     return high_survival_rate_period_length_ > 0;
   }
 
   void SelectScavengingVisitorsTable();
 
+  void StartIdleRound() {
+    mark_sweeps_since_idle_round_started_ = 0;
+    ms_count_at_last_idle_notification_ = ms_count_;
+  }
+
+  void FinishIdleRound() {
+    mark_sweeps_since_idle_round_started_ = kMaxMarkSweepsInIdleRound;
+    gc_count_when_last_idle_round_finished_ = gc_count_;
+  }
+
+  bool EnoughGarbageSinceLastIdleRound() {
+    return (gc_count_ - gc_count_when_last_idle_round_finished_ > 4);

[ulan, 2011/11/11 13:27:26]

We agreed to count only scavenges here, but for that I need to add another
counter and code to maintain the counter. Since full GC are rare anyway, I think
gc_count_ is good enough until we add much better counters like "promoted bytes
since last full GC".

[Erik Corry, 2011/11/14 23:05:17]

I really think we should just add the extra counter here.  It's only about 3
lines.  You are counting scavenges to decide to do a full GC.  If you count full
GCs too then you risk a situation where a full GC contributes to the decision to
do another full GC.  That sounds like the sort of positive feedback that should
be avoided on principle.

[ulan, 2011/11/15 09:08:43]

Done.

+  }
+
+  bool WorthStartingGCWhenIdle() {
+    if (contexts_disposed_ > 0) {
+      return true;
+    }
+    if (mark_sweeps_since_idle_round_started_ < kMaxMarkSweepsInIdleRound) {
+      return incremental_marking()->WorthActivating();
+    }
+    if (EnoughGarbageSinceLastIdleRound()) {
+      return incremental_marking()->WorthActivating() &&
+             NextGCIsLikelyToBeFull();
+    }
+    return false;
+  }
+
+  // Returns true if no more GC work is left.
+  bool IdleGlobalGC();
+
   static const int kInitialSymbolTableSize = 2048;
   static const int kInitialEvalCacheSize = 64;
 
   // Maximum GC pause.
   int max_gc_pause_;
 
   // Maximum size of objects alive after GC.
   intptr_t max_alive_after_gc_;
 
   // Minimal interval between two subsequent collections.
   int min_in_mutator_;
 
   // Size of objects alive after last GC.
   intptr_t alive_after_last_gc_;
 
   double last_gc_end_timestamp_;
 
   MarkCompactCollector mark_compact_collector_;
 
   StoreBuffer store_buffer_;
 
   Marking marking_;
 
   IncrementalMarking incremental_marking_;
 
   int number_idle_notifications_;
   unsigned int last_idle_notification_gc_count_;
   bool last_idle_notification_gc_count_init_;
 
+  bool idle_notification_will_schedule_next_gc_;
+  int mark_sweeps_since_idle_round_started_;
+  int ms_count_at_last_idle_notification_;
+  unsigned int gc_count_at_last_idle_gc_;
+  unsigned int gc_count_when_last_idle_round_finished_;
+
+  static const int kMaxMarkSweepsInIdleRound = 7;
+
   // Shared state read by the scavenge collector and set by ScavengeObject.
   PromotionQueue promotion_queue_;
 
   // Flag is set when the heap has been configured.  The heap can be repeatedly
   // configured through the API until it is setup.
   bool configured_;
 
   ExternalStringTable external_string_table_;
 
   VisitorDispatchTable<ScavengingCallback> scavenging_visitors_table_;
@@ skipping 684 matching lines @@
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #undef HEAP
 
 #endif  // V8_HEAP_H_