[heap] Do not require kRingBufferMaxSize samples for estimating compaction speed

src/heap/gc-tracer.cc

 // 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.
 
 #include "src/heap/gc-tracer.h"
 
 #include "src/counters.h"
 #include "src/heap/heap-inl.h"
 #include "src/isolate.h"
 
@@ skipping 713 matching lines @@
     ++iter;
   }
 
   if (durations == 0.0) return 0;
   // Make sure the result is at least 1.
   return Max<size_t>(static_cast<size_t>(bytes / durations + 0.5), 1);
 }
 
 
 intptr_t GCTracer::CompactionSpeedInBytesPerMillisecond() const {
-  if (compaction_events_.size() < kRingBufferMaxSize) return 0;
+  if (compaction_events_.size() == 0) return 0;
   intptr_t bytes = 0;
   double durations = 0.0;
   CompactionEventBuffer::const_iterator iter = compaction_events_.begin();
   while (iter != compaction_events_.end()) {
     bytes += iter->live_bytes_compacted;
     durations += iter->duration;
     ++iter;
   }
 
   if (durations == 0.0) return 0;
@@ skipping 147 matching lines @@
 
 
 bool GCTracer::SurvivalEventsRecorded() const {
   return survival_events_.size() > 0;
 }
 
 
 void GCTracer::ResetSurvivalEvents() { survival_events_.reset(); }
 }  // namespace internal
 }  // namespace v8