Replace reduce-memory mode in idle notification with delayed clean-up GC.

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 {
 namespace internal {
 
 enum GCIdleTimeActionType {
   DONE,
   DO_NOTHING,
   DO_INCREMENTAL_MARKING,
   DO_SCAVENGE,
   DO_FULL_GC,
   DO_FINALIZE_SWEEPING
 };
 
 
 class GCIdleTimeAction {
  public:
   static GCIdleTimeAction Done() {
     GCIdleTimeAction result;
     result.type = DONE;
     result.parameter = 0;
     result.additional_work = false;
-    result.reduce_memory = false;
     return result;
   }
 
   static GCIdleTimeAction Nothing() {
     GCIdleTimeAction result;
     result.type = DO_NOTHING;
     result.parameter = 0;
     result.additional_work = false;
-    result.reduce_memory = false;
     return result;
   }
 
-  static GCIdleTimeAction IncrementalMarking(intptr_t step_size,
-                                             bool reduce_memory) {
+  static GCIdleTimeAction IncrementalMarking(intptr_t step_size) {
     GCIdleTimeAction result;
     result.type = DO_INCREMENTAL_MARKING;
     result.parameter = step_size;
     result.additional_work = false;
-    result.reduce_memory = reduce_memory;
     return result;
   }
 
   static GCIdleTimeAction Scavenge() {
     GCIdleTimeAction result;
     result.type = DO_SCAVENGE;
     result.parameter = 0;
     result.additional_work = false;
-    // TODO(ulan): add reduce_memory argument and shrink new space size if
-    // reduce_memory = true.
-    result.reduce_memory = false;
     return result;
   }
 
-  static GCIdleTimeAction FullGC(bool reduce_memory) {
+  static GCIdleTimeAction FullGC() {
     GCIdleTimeAction result;
     result.type = DO_FULL_GC;
     result.parameter = 0;
     result.additional_work = false;
-    result.reduce_memory = reduce_memory;
     return result;
   }
 
   static GCIdleTimeAction FinalizeSweeping() {
     GCIdleTimeAction result;
     result.type = DO_FINALIZE_SWEEPING;
     result.parameter = 0;
     result.additional_work = false;
-    result.reduce_memory = false;
     return result;
   }
 
   void Print();
 
   GCIdleTimeActionType type;
   intptr_t parameter;
   bool additional_work;
-  bool reduce_memory;
 };
 
 
 class GCTracer;
 
 // The idle time handler makes decisions about which garbage collection
 // operations are executing during IdleNotification.
 class GCIdleTimeHandler {
  public:
   // If we haven't recorded any incremental marking events yet, we carefully
@@ skipping 23 matching lines @@
   // EstimateFinalIncrementalMarkCompactTime.
   static const size_t kMaxFinalIncrementalMarkCompactTimeInMs;
 
   // This is the maximum scheduled idle time. Note that it can be more than
   // 16.66 ms when there is currently no rendering going on.
   static const size_t kMaxScheduledIdleTime = 50;
 
   // The maximum idle time when frames are rendered is 16.66ms.
   static const size_t kMaxFrameRenderingIdleTime = 17;
 
+  static const int kMinBackgroundIdleTime = 900;
+
   // We conservatively assume that in the next kTimeUntilNextIdleEvent ms
   // no idle notification happens.
   static const size_t kTimeUntilNextIdleEvent = 100;
 
   // If we haven't recorded any scavenger events yet, we use a conservative
   // lower bound for the scavenger speed.
   static const size_t kInitialConservativeScavengeSpeed = 100 * KB;
 
   // The minimum size of allocated new space objects to trigger a scavenge.
   static const size_t kMinimumNewSpaceSizeToPerformScavenge = MB / 2;
 
   // If contexts are disposed at a higher rate a full gc is triggered.
   static const double kHighContextDisposalRate;
 
   // 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 MarkCompact GCs before transitioning to the
-  // kReduceLatency mode.
-  static const int kMarkCompactsBeforeMutatorIsActive = 1;
-
-  // Mutator is considered idle if
-  // 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 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;
+  static const int kMaxNoProgressIdleTimes = 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;
     bool has_low_allocation_rate;
     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),
-        next_gc_likely_to_collect_more_(false),
-        mode_(kReduceLatency) {}
+  GCIdleTimeHandler() : idle_times_which_made_no_progress_(0) {}
 
   GCIdleTimeAction Compute(double idle_time_in_ms, HeapState heap_state);
 
-  void NotifyIdleMarkCompact() { ++idle_mark_compacts_; }
-
-  void NotifyMarkCompact(bool next_gc_likely_to_collect_more) {
-    next_gc_likely_to_collect_more_ = next_gc_likely_to_collect_more;
-    ++mark_compacts_;
-  }
-
-  void NotifyScavenge() { ++scavenges_; }
+  void ResetNoProgressCounter() { idle_times_which_made_no_progress_ = 0; }
 
   static size_t EstimateMarkingStepSize(size_t idle_time_in_ms,
                                         size_t marking_speed_in_bytes_per_ms);
 
   static size_t EstimateMarkCompactTime(
       size_t size_of_objects, size_t mark_compact_speed_in_bytes_per_ms);
 
   static size_t EstimateFinalIncrementalMarkCompactTime(
       size_t size_of_objects, size_t mark_compact_speed_in_bytes_per_ms);
 
   static bool ShouldDoMarkCompact(size_t idle_time_in_ms,
                                   size_t size_of_objects,
                                   size_t mark_compact_speed_in_bytes_per_ms);
 
   static bool ShouldDoContextDisposalMarkCompact(int context_disposed,
                                                  double contexts_disposal_rate);
 
   static bool ShouldDoFinalIncrementalMarkCompact(
       size_t idle_time_in_ms, size_t size_of_objects,
       size_t final_incremental_mark_compact_speed_in_bytes_per_ms);
 
   static bool ShouldDoOverApproximateWeakClosure(size_t idle_time_in_ms);
 
   static bool ShouldDoScavenge(
       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 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 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_;
-
-  bool next_gc_likely_to_collect_more_;
-
-  Mode mode_;
+  // Idle notifications with no progress.
+  int idle_times_which_made_no_progress_;
 
   DISALLOW_COPY_AND_ASSIGN(GCIdleTimeHandler);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_GC_IDLE_TIME_HANDLER_H_