Use more conservative average promotion ratio for initial heap size.

src/heap/gc-tracer.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_TRACER_H_
 #define V8_HEAP_GC_TRACER_H_
 
 #include "src/base/platform/platform.h"
 
 namespace v8 {
@@ skipping 146 matching lines @@
     // Default constructor leaves the event uninitialized.
     ContextDisposalEvent() {}
 
     explicit ContextDisposalEvent(double time);
 
     // Time when context disposal event happened.
     double time_;
   };
 
 
-  class SurvivalEvent {
+  class PromotionEvent {
    public:
     // Default constructor leaves the event uninitialized.
-    SurvivalEvent() {}
+    PromotionEvent() {}
 
-    explicit SurvivalEvent(double survival_rate);
+    explicit PromotionEvent(double promotion_ratio);
 
-    double survival_rate_;
+    double promotion_ratio_;
   };
 
 
   class Event {
    public:
     enum Type {
       SCAVENGER = 0,
       MARK_COMPACTOR = 1,
       INCREMENTAL_MARK_COMPACTOR = 2,
       START = 3
@@ skipping 91 matching lines @@
 
   static const size_t kRingBufferMaxSize = 10;
 
   typedef RingBuffer<Event, kRingBufferMaxSize> EventBuffer;
 
   typedef RingBuffer<AllocationEvent, kRingBufferMaxSize> AllocationEventBuffer;
 
   typedef RingBuffer<ContextDisposalEvent, kRingBufferMaxSize>
       ContextDisposalEventBuffer;
 
-  typedef RingBuffer<SurvivalEvent, kRingBufferMaxSize> SurvivalEventBuffer;
+  typedef RingBuffer<PromotionEvent, kRingBufferMaxSize> PromotionEventBuffer;
 
   explicit GCTracer(Heap* heap);
 
   // Start collecting data.
   void Start(GarbageCollector collector, const char* gc_reason,
              const char* collector_reason);
 
   // Stop collecting data and print results.
   void Stop(GarbageCollector collector);
 
   // Log an allocation throughput event.
   void AddNewSpaceAllocationTime(double duration, intptr_t allocation_in_bytes);
 
   void AddContextDisposalTime(double time);
 
-  void AddSurvivalRate(double survival_rate);
+  void AddPromotionRatio(double promotion_ratio);
 
   // Log an incremental marking step.
   void AddIncrementalMarkingStep(double duration, intptr_t bytes);
 
   // Log time spent in marking.
   void AddMarkingTime(double duration) {
     cumulative_marking_duration_ += duration;
   }
 
   // Time spent in marking.
@@ skipping 67 matching lines @@
   // Allocation throughput in the new space in bytes/millisecond.
   // Returns 0 if no events have been recorded.
   intptr_t NewSpaceAllocationThroughputInBytesPerMillisecond() const;
 
   // Computes the context disposal rate in milliseconds. It takes the time
   // frame of the first recorded context disposal to the current time and
   // divides it by the number of recorded events.
   // Returns 0 if no events have been recorded.
   double ContextDisposalRateInMilliseconds() const;
 
-  // Computes the average survival rate based on the last recorded survival
+  // Computes the average promotion ratio based on the last recorded promotion
   // events.
   // Returns 0 if no events have been recorded.
-  double AverageSurvivalRate() const;
+  double AveragePromotionRatio() const;
 
   // Returns true if at least one survival event was recorded.
   bool SurvivalEventsRecorded() const;
 
   // Discard all recorded survival events.
   void ResetSurvivalEvents();
 
  private:
   // Print one detailed trace line in name=value format.
   // TODO(ernstm): Move to Heap.
@@ skipping 40 matching lines @@
 
   // RingBuffers for INCREMENTAL_MARK_COMPACTOR events.
   EventBuffer incremental_mark_compactor_events_;
 
   // RingBuffer for allocation events.
   AllocationEventBuffer allocation_events_;
 
   // RingBuffer for context disposal events.
   ContextDisposalEventBuffer context_disposal_events_;
 
-  // RingBuffer for survival events.
-  SurvivalEventBuffer survival_events_;
+  // RingBuffer for promotion events.
+  PromotionEventBuffer promotion_events_;
 
   // Cumulative number of incremental marking steps since creation of tracer.
   int cumulative_incremental_marking_steps_;
 
   // Cumulative size of incremental marking steps (in bytes) since creation of
   // tracer.
   intptr_t cumulative_incremental_marking_bytes_;
 
   // Cumulative duration of incremental marking steps since creation of tracer.
   double cumulative_incremental_marking_duration_;
@@ skipping 24 matching lines @@
 
   // Counts how many tracers were started without stopping.
   int start_counter_;
 
   DISALLOW_COPY_AND_ASSIGN(GCTracer);
 };
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_GC_TRACER_H_