[heap] Use RAIL mode for initial heap sizing

src/heap/heap.h

 // 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.
 
 #ifndef V8_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 568 matching lines @@
 
   // Support for partial snapshots.  After calling this we have a linear
   // space to write objects in each space.
   struct Chunk {
     uint32_t size;
     Address start;
     Address end;
   };
   typedef List<Chunk> Reservation;
 
-  static const int kInitalOldGenerationLimitFactor = 2;
-
 #if V8_OS_ANDROID
   // Don't apply pointer multiplier on Android since it has no swap space and
   // should instead adapt it's heap size based on available physical memory.
   static const int kPointerMultiplier = 1;
 #else
   static const int kPointerMultiplier = i::kPointerSize / 4;
 #endif
 
   // The new space size has to be a power of 2. Sizes are in MB.
   static const int kMaxSemiSpaceSizeLowMemoryDevice = 1 * kPointerMultiplier;
@@ skipping 1100 matching lines @@
 
   // Record statistics before and after garbage collection.
   void ReportStatisticsBeforeGC();
   void ReportStatisticsAfterGC();
 
   // Creates and installs the full-sized number string cache.
   int FullSizeNumberStringCacheLength();
   // Flush the number to string cache.
   void FlushNumberStringCache();
 
-  void ConfigureInitialOldGenerationSize();
-
   bool HasLowYoungGenerationAllocationRate();
   bool HasLowOldGenerationAllocationRate();
   double YoungGenerationMutatorUtilization();
   double OldGenerationMutatorUtilization();
 
   void ReduceNewSpaceSize();
 
   GCIdleTimeHeapState ComputeHeapState();
 
   bool PerformIdleTimeAction(GCIdleTimeAction action,
@@ skipping 68 matching lines @@
   void ProcessAllWeakReferences(WeakObjectRetainer* retainer);
   void ProcessYoungWeakReferences(WeakObjectRetainer* retainer);
   void ProcessNativeContexts(WeakObjectRetainer* retainer);
   void ProcessAllocationSites(WeakObjectRetainer* retainer);
   void ProcessWeakListRoots(WeakObjectRetainer* retainer);
 
   // ===========================================================================
   // GC statistics. ============================================================
   // ===========================================================================
 
-  inline intptr_t OldGenerationSpaceAvailable() {
-    return old_generation_allocation_limit_ - PromotedTotalSize();
-  }
+  intptr_t OldGenerationSpaceAvailable();
 
   void UpdateTotalGCTime(double duration);
 
   bool MaximumSizeScavenge() { return maximum_size_scavenges_ > 0; }
 
   // ===========================================================================
   // Growing strategy. =========================================================
   // ===========================================================================
 
+  static const int kInitalOldGenerationLimitFactor = 2;
+
+  // For some webpages RAIL mode does not switch from PERFORMANCE_LOAD.
+  // This constant limits the effect of load RAIL mode on GC.
+  // The value is arbitrary and chosen as the largest load time observed in
+  // v8 browsing benchmarks.
+  static const int kMaxLoadTimeMs = 3000;

[Hannes Payer (out of office), 2016/10/11 09:02:09]

Why 3 seconds? Load was originally aiming for 1 second.

[ulan, 2016/12/02 11:42:28]

The value is chosen as the largest load time observed in v8 browsing benchmarks.

+
+  bool ShouldOptimizeForLoadTime();
+
   // Decrease the allocation limit if the new limit based on the given
   // parameters is lower than the current limit.
   void DampenOldGenerationAllocationLimit(intptr_t old_gen_size,
                                           double gc_speed,
                                           double mutator_speed);
 
 
   // Calculates the allocation limit based on a given growing factor and a
   // given old generation size.
   intptr_t CalculateOldGenerationAllocationLimit(double factor,
@@ skipping 266 matching lines @@
   // This can be calculated directly from a pointer to the heap; however, it is
   // more expedient to get at the isolate directly from within Heap methods.
   Isolate* isolate_;
 
   Object* roots_[kRootListLength];
 
   size_t code_range_size_;
   int max_semi_space_size_;
   int initial_semispace_size_;
   intptr_t max_old_generation_size_;
-  intptr_t initial_old_generation_size_;
-  bool old_generation_size_configured_;
   intptr_t max_executable_size_;
   size_t maximum_committed_;
 
   // For keeping track of how much data has survived
   // scavenge since last new space expansion.
   intptr_t survived_since_last_expansion_;
 
   // ... and since the last scavenge.
   intptr_t survived_last_scavenge_;
 
@@ skipping 528 matching lines @@
   }
 
  private:
   Heap* heap_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_