Add mode to reduce memory usage in idle notification.

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

Index: src/heap/gc-idle-time-handler.h
diff --git a/src/heap/gc-idle-time-handler.h b/src/heap/gc-idle-time-handler.h
index ed89b8bc770a07aac81313ddc21ce8487c67565d..ed77be050a45f4bbfdc094c5e08821e892a533a3 100644
--- a/src/heap/gc-idle-time-handler.h
+++ b/src/heap/gc-idle-time-handler.h
@@ -27,6 +27,7 @@ class GCIdleTimeAction {
     result.type = DONE;
     result.parameter = 0;
     result.additional_work = false;
+    result.reduce_memory = false;
     return result;
   }
 
@@ -35,14 +36,17 @@ class GCIdleTimeAction {
     result.type = DO_NOTHING;
     result.parameter = 0;
     result.additional_work = false;
+    result.reduce_memory = false;
     return result;
   }
 
-  static GCIdleTimeAction IncrementalMarking(intptr_t step_size) {
+  static GCIdleTimeAction IncrementalMarking(intptr_t step_size,
+                                             bool reduce_memory) {
     GCIdleTimeAction result;
     result.type = DO_INCREMENTAL_MARKING;
     result.parameter = step_size;
     result.additional_work = false;
+    result.reduce_memory = reduce_memory;
     return result;
   }
 
@@ -51,14 +55,16 @@ class GCIdleTimeAction {
     result.type = DO_SCAVENGE;
     result.parameter = 0;
     result.additional_work = false;
+    result.reduce_memory = false;
     return result;
   }
 
-  static GCIdleTimeAction FullGC() {
+  static GCIdleTimeAction FullGC(bool reduce_memory) {
     GCIdleTimeAction result;
     result.type = DO_FULL_GC;
     result.parameter = 0;
     result.additional_work = false;
+    result.reduce_memory = reduce_memory;
     return result;
   }
 
@@ -67,6 +73,7 @@ class GCIdleTimeAction {
     result.type = DO_FINALIZE_SWEEPING;
     result.parameter = 0;
     result.additional_work = false;
+    result.reduce_memory = false;
     return result;
   }
 
@@ -75,6 +82,7 @@ class GCIdleTimeAction {
   GCIdleTimeActionType type;
   intptr_t parameter;
   bool additional_work;
+  bool reduce_memory;
 };
 
 
@@ -111,13 +119,6 @@ class GCIdleTimeHandler {
   // EstimateFinalIncrementalMarkCompactTime.
   static const size_t kMaxFinalIncrementalMarkCompactTimeInMs;
 
-  // Number of idle mark-compact events, after which idle handler will finish
-  // idle round.
-  static const int kMaxMarkCompactsInIdleRound;
-
-  // Number of scavenges that will trigger start of new idle round.
-  static const int kIdleScavengeThreshold;
-
   // 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;
@@ -141,10 +142,22 @@ class GCIdleTimeHandler {
 
   static const size_t kMinTimeForOverApproximatingWeakClosureInMs;
 
-  // Number of times we will return a Nothing action per Idle round 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 kMaxNoProgressIdleTimesPerIdleRound = 10;
+  // 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 from the kDone mode.

[Hannes Payer (out of office), 2015/05/04 11:20:36]

to kReduceLatency

[ulan, 2015/05/05 12:10:13]

Done.

+  static const int kGCsBeforeMutatorIsActive = 7;
+
+  // Mutator is considered idle if
+  // 1) there is an idle notification with time >= kMaxLongIdleTime,
+  // 2) or there are kLongIdleNotificationsBeforeMutatorIsIdle idle
+  // notifications
+  //    with time >= kMinLongIdleTime and without any mutator GC in between.
+  static const int kMinLongIdleTime = kMaxFrameRenderingIdleTime + 1;
+  static const int kMaxLongIdleTime = 1000;
+  static const int kLongIdleNotificationsBeforeMutatorIsIdle = 20;
+
 
   class HeapState {
    public:
@@ -167,23 +180,19 @@ class GCIdleTimeHandler {
   };
 
   GCIdleTimeHandler()
-      : mark_compacts_since_idle_round_started_(0),
-        scavenges_since_last_idle_round_(0),
-        idle_times_which_made_no_progress_since_last_idle_round_(0) {}
+      : idle_mark_compacts_(0),
+        mark_compacts_(0),
+        scavenges_(0),
+        long_idle_notifications_(0),
+        mode_(kReduceLatency) {}
 
   GCIdleTimeAction Compute(double idle_time_in_ms, HeapState heap_state);
 
-  void NotifyIdleMarkCompact() {
-    if (mark_compacts_since_idle_round_started_ < kMaxMarkCompactsInIdleRound) {
-      ++mark_compacts_since_idle_round_started_;
-      if (mark_compacts_since_idle_round_started_ ==
-          kMaxMarkCompactsInIdleRound) {
-        scavenges_since_last_idle_round_ = 0;
-      }
-    }
-  }
+  void NotifyIdleMarkCompact() { ++idle_mark_compacts_; }
 
-  void NotifyScavenge() { ++scavenges_since_last_idle_round_; }
+  void NotifyMarkCompact() { ++mark_compacts_; }
+
+  void NotifyScavenge() { ++scavenges_; }
 
   static size_t EstimateMarkingStepSize(size_t idle_time_in_ms,
                                         size_t marking_speed_in_bytes_per_ms);
@@ -213,23 +222,22 @@ class GCIdleTimeHandler {
       size_t new_space_allocation_throughput_in_bytes_per_ms);
 
  private:
-  GCIdleTimeAction NothingOrDone();
-
-  void StartIdleRound() {
-    mark_compacts_since_idle_round_started_ = 0;
-    idle_times_which_made_no_progress_since_last_idle_round_ = 0;
-  }
-  bool IsMarkCompactIdleRoundFinished() {
-    return mark_compacts_since_idle_round_started_ ==
-           kMaxMarkCompactsInIdleRound;
-  }
-  bool EnoughGarbageSinceLastIdleRound() {
-    return scavenges_since_last_idle_round_ >= kIdleScavengeThreshold;
-  }
-
-  int mark_compacts_since_idle_round_started_;
-  int scavenges_since_last_idle_round_;
-  int idle_times_which_made_no_progress_since_last_idle_round_;
+  enum Mode { kReduceLatency, kReduceMemory, kDone };
+
+  bool IsMutatorActive(int contexts_disposed, int gcs);
+  bool IsMutatorIdle(int long_idle_notifications, int gcs);
+  void UpdateCounters(double idle_time_in_ms);
+  void ResetCounters();
+  Mode NextMode(const HeapState& heap_state);
+  GCIdleTimeAction Step(double idle_time_in_ms, const HeapState& heap_state,
+                        bool reduce_memory);
+
+  int idle_mark_compacts_;
+  int mark_compacts_;
+  int scavenges_;
+  int long_idle_notifications_;
+
+  Mode mode_;
 
   DISALLOW_COPY_AND_ASSIGN(GCIdleTimeHandler);
 };