Restore NothingOrDone action in idle time handler.

src/heap/gc-idle-time-handler.h

 // Copyright 2014 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.
 
 #ifndef V8_HEAP_GC_IDLE_TIME_HANDLER_H_
 #define V8_HEAP_GC_IDLE_TIME_HANDLER_H_
 
 #include "src/globals.h"
 
 namespace v8 {
@@ skipping 133 matching lines @@
 
   // Incremental marking step time.
   static const size_t kIncrementalMarkingStepTimeInMs = 1;
 
   static const size_t kMinTimeForOverApproximatingWeakClosureInMs;
 
   // The number of idle MarkCompact GCs to perform before transitioning to
   // the kDone mode.
   static const int kMaxIdleMarkCompacts = 3;
 
-  // The number of mutator GCs before transitioning to the kReduceLatency mode.
-  static const int kGCsBeforeMutatorIsActive = 7;
+  // The number of mutator MarkCompact GCs before transitioning to the
+  // kReduceLatency mode.
+  static const int kMarkCompactsBeforeMutatorIsActive = 1;
 
   // Mutator is considered idle if
-  // 1) there is an idle notification with time >= kLargeLongIdleTime,
-  // 2) or there are kLongIdleNotificationsBeforeMutatorIsIdle idle
-  // notifications
-  //    with time >= kMinLongIdleTime and without any mutator GC in between.
+  // 1) there are N idle notification with time >= kMinBackgroundIdleTime,
+  // 2) or there are M idle notifications with time >= kMinLongIdleTime
+  // without any mutator GC in between.
+  // Where N = kBackgroundIdleNotificationsBeforeMutatorIsIdle,
+  //       M = kLongIdleNotificationsBeforeMutatorIsIdle
   static const int kMinLongIdleTime = kMaxFrameRenderingIdleTime + 1;
-  static const int kLargeLongIdleTime = 900;
-  static const int kLongIdleNotificationsBeforeMutatorIsIdle = 600;
-
+  static const int kMinBackgroundIdleTime = 900;
+  static const int kBackgroundIdleNotificationsBeforeMutatorIsIdle = 2;
+  static const int kLongIdleNotificationsBeforeMutatorIsIdle = 50;
+  // Number of times we will return a Nothing action in the current mode
+  // despite having idle time available before we returning a Done action to
+  // ensure we don't keep scheduling idle tasks and making no progress.
+  static const int kMaxNoProgressIdleTimesPerMode = 10;
 
   class HeapState {
    public:
     void Print();
 
     int contexts_disposed;
     double contexts_disposal_rate;
     size_t size_of_objects;
     bool incremental_marking_stopped;
     bool can_start_incremental_marking;
     bool sweeping_in_progress;
     bool sweeping_completed;
     size_t mark_compact_speed_in_bytes_per_ms;
     size_t incremental_marking_speed_in_bytes_per_ms;
     size_t final_incremental_mark_compact_speed_in_bytes_per_ms;
     size_t scavenge_speed_in_bytes_per_ms;
     size_t used_new_space_size;
     size_t new_space_capacity;
     size_t new_space_allocation_throughput_in_bytes_per_ms;
   };
 
   GCIdleTimeHandler()
       : idle_mark_compacts_(0),
         mark_compacts_(0),
         scavenges_(0),
         long_idle_notifications_(0),
+        background_idle_notifications_(0),
+        idle_times_which_made_no_progress_per_mode_(0),
         mode_(kReduceLatency) {}
 
   GCIdleTimeAction Compute(double idle_time_in_ms, HeapState heap_state);
 
   void NotifyIdleMarkCompact() { ++idle_mark_compacts_; }
 
   void NotifyMarkCompact() { ++mark_compacts_; }
 
   void NotifyScavenge() { ++scavenges_; }
 
@@ skipping 23 matching lines @@
       size_t idle_time_in_ms, size_t new_space_size, size_t used_new_space_size,
       size_t scavenger_speed_in_bytes_per_ms,
       size_t new_space_allocation_throughput_in_bytes_per_ms);
 
   enum Mode { kReduceLatency, kReduceMemory, kDone };
 
   Mode mode() { return mode_; }
 
  private:
   bool IsMutatorActive(int contexts_disposed, int gcs);
-  bool IsMutatorIdle(int long_idle_notifications, int gcs);
+  bool IsMutatorIdle(int long_idle_notifications,
+                     int background_idle_notifications, int gcs);
   void UpdateCounters(double idle_time_in_ms);
   void ResetCounters();
   Mode NextMode(const HeapState& heap_state);
   GCIdleTimeAction Action(double idle_time_in_ms, const HeapState& heap_state,
                           bool reduce_memory);
+  GCIdleTimeAction NothingOrDone();
 
   int idle_mark_compacts_;
   int mark_compacts_;
   int scavenges_;
-  // The number of long idle notifications with no mutator GC happening
+  // The number of long idle notifications with no GC happening
   // between the notifications.
   int long_idle_notifications_;
+  // The number of background idle notifications with no GC happening
+  // between the notifications.
+  int background_idle_notifications_;
+  // Idle notifications with no progress in the current mode.
+  int idle_times_which_made_no_progress_per_mode_;
 
   Mode mode_;
 
   DISALLOW_COPY_AND_ASSIGN(GCIdleTimeHandler);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_GC_IDLE_TIME_HANDLER_H_