Memory reducer should use the current allocation rate instead of the overall allocation rate.

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 270 matching lines @@
     double pure_incremental_marking_duration;
 
     // Longest incremental marking step since start of marking.
     // (value at start of event)
     double longest_incremental_marking_step;
 
     // Amounts of time spent in different scopes during GC.
     double scopes[Scope::NUMBER_OF_SCOPES];
   };
 
+  static const int kThroughputTimeFrameMs = 5000;
+
   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;
@@ skipping 108 matching lines @@
   // last time_ms milliseconds.
   // Returns 0 if no allocation events have been recorded.
   size_t OldGenerationAllocationThroughputInBytesPerMillisecond(
       double time_ms = 0) const;
 
   // Allocation throughput in heap in bytes/millisecond in the last time_ms
   // milliseconds.
   // Returns 0 if no allocation events have been recorded.
   size_t AllocationThroughputInBytesPerMillisecond(double time_ms) const;
 
+  // Allocation throughput in new space in bytes/milliseconds in
+  // the last five seconds.
+  // Returns 0 if no allocation events have been recorded.
+  size_t CurrentNewSpaceAllocationThroughputInBytesPerMillisecond() const;
+
   // Allocation throughput in old generation in bytes/milliseconds in
   // the last five seconds.
   // Returns 0 if no allocation events have been recorded.
   size_t CurrentOldGenerationAllocationThroughputInBytesPerMillisecond() 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;
@@ skipping 114 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_