Reland of "[heap] Switch to 500k pages"

src/heap/mark-compact.cc

 // Copyright 2012 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/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 582 matching lines @@
   return NULL;
 }
 
 
 void MarkCompactCollector::ComputeEvacuationHeuristics(
     int area_size, int* target_fragmentation_percent,
     int* max_evacuated_bytes) {
   // For memory reducing and optimize for memory mode we directly define both
   // constants.
   const int kTargetFragmentationPercentForReduceMemory = 20;
-  const int kMaxEvacuatedBytesForReduceMemory = 12 * Page::kPageSize;
+  const int kMaxEvacuatedBytesForReduceMemory = 12 * MB;
   const int kTargetFragmentationPercentForOptimizeMemory = 20;
   const int kMaxEvacuatedBytesForOptimizeMemory = 6 * MB;
 
   // For regular mode (which is latency critical) we define less aggressive
   // defaults to start and switch to a trace-based (using compaction speed)
   // approach as soon as we have enough samples.
   const int kTargetFragmentationPercent = 70;
-  const int kMaxEvacuatedBytes = 4 * Page::kPageSize;
+  const int kMaxEvacuatedBytes = 4 * MB;
   // Time to take for a single area (=payload of page). Used as soon as there
   // exist enough compaction speed samples.
-  const int kTargetMsPerArea = 1;
+  const float kTargetMsPerArea = 0.5;
 
   if (heap()->ShouldReduceMemory()) {
     *target_fragmentation_percent = kTargetFragmentationPercentForReduceMemory;
     *max_evacuated_bytes = kMaxEvacuatedBytesForReduceMemory;
   } else if (heap()->ShouldOptimizeForMemoryUsage()) {
     *target_fragmentation_percent =
         kTargetFragmentationPercentForOptimizeMemory;
     *max_evacuated_bytes = kMaxEvacuatedBytesForOptimizeMemory;
   } else {
     const double estimated_compaction_speed =
@@ skipping 2591 matching lines @@
 
 int MarkCompactCollector::NumberOfParallelCompactionTasks(int pages,
                                                           intptr_t live_bytes) {
   if (!FLAG_parallel_compaction) return 1;
   // Compute the number of needed tasks based on a target compaction time, the
   // profiled compaction speed and marked live memory.
   //
   // The number of parallel compaction tasks is limited by:
   // - #evacuation pages
   // - (#cores - 1)
-  const double kTargetCompactionTimeInMs = 1;
+  const double kTargetCompactionTimeInMs = .5;
   const int kNumSweepingTasks = 3;
 
   double compaction_speed =
       heap()->tracer()->CompactionSpeedInBytesPerMillisecond();
 
   const int available_cores = Max(
       1, static_cast<int>(
              V8::GetCurrentPlatform()->NumberOfAvailableBackgroundThreads()) -
              kNumSweepingTasks - 1);
   int tasks;
@@ skipping 800 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8