Force scavenge in idle notification if we estimate that it will take long.

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 95 matching lines @@
   // Number of scavenges that will trigger start of new idle round.
   static const int kIdleScavengeThreshold;
 
   // Heap size threshold below which we prefer mark-compact over incremental
   // step.
   static const size_t kSmallHeapSize = 2 * kPointerSize * MB;
 
   // That is the maximum idle time we will have during frame rendering.
   static const size_t kMaxFrameRenderingIdleTime = 16;
 
-  // If less than that much memory is left in the new space, we consider it
-  // as almost full and force a new space collection earlier in the idle time.
-  static const size_t kNewSpaceAlmostFullTreshold = 100 * KB;
-
   // 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;
 
   struct HeapState {
     int contexts_disposed;
     size_t size_of_objects;
     bool incremental_marking_stopped;
     bool can_start_incremental_marking;
     bool sweeping_in_progress;
     size_t mark_compact_speed_in_bytes_per_ms;
     size_t incremental_marking_speed_in_bytes_per_ms;
     size_t scavenge_speed_in_bytes_per_ms;
-    size_t available_new_space_memory;
+    size_t used_new_space_size;
     size_t new_space_capacity;
     size_t new_space_allocation_throughput_in_bytes_per_ms;
   };
 
   GCIdleTimeHandler()
       : mark_compacts_since_idle_round_started_(0),
         scavenges_since_last_idle_round_(0) {}
 
   GCIdleTimeAction Compute(size_t 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 NotifyScavenge() { ++scavenges_since_last_idle_round_; }
 
   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 EstimateScavengeTime(size_t new_space_size,
-                                     size_t scavenger_speed_in_bytes_per_ms);
-
-  static bool ScavangeMayHappenSoon(
-      size_t available_new_space_memory,
+  static bool DoScavenge(
+      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);
 
  private:
   void StartIdleRound() { mark_compacts_since_idle_round_started_ = 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_;
 
   DISALLOW_COPY_AND_ASSIGN(GCIdleTimeHandler);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_GC_IDLE_TIME_HANDLER_H_