Reduce new space size when average scavenging time is high

src/heap/heap.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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 720 matching lines @@
 
 #ifdef DEBUG
   ReportStatisticsAfterGC();
 #endif  // DEBUG
 
   // Remember the last top pointer so that we can later find out
   // whether we allocated in new space since the last GC.
   new_space_top_after_last_gc_ = new_space()->top();
   last_gc_time_ = MonotonicallyIncreasingTimeInMs();
 
-  ReduceNewSpaceSize(
-      tracer()->CurrentAllocationThroughputInBytesPerMillisecond());
+  ReduceNewSpaceSize();
 }
 
 
 void Heap::PreprocessStackTraces() {
   if (!weak_stack_trace_list()->IsWeakFixedArray()) return;
   WeakFixedArray* array = WeakFixedArray::cast(weak_stack_trace_list());
   int length = array->Length();
   for (int i = 0; i < length; i++) {
     if (array->IsEmptySlot(i)) continue;
     FixedArray* elements = FixedArray::cast(array->Get(i));
@@ skipping 676 matching lines @@
   VerifyNonPointerSpacePointersVisitor v(heap);
   HeapObjectIterator code_it(heap->code_space());
   for (HeapObject* object = code_it.Next(); object != NULL;
        object = code_it.Next())
     object->Iterate(&v);
 }
 #endif  // VERIFY_HEAP
 
 
 void Heap::CheckNewSpaceExpansionCriteria() {
+  if (!HasLowYoungGenerationAllocationUtilization()) {
   if (FLAG_experimental_new_space_growth_heuristic) {
     if (new_space_.TotalCapacity() < new_space_.MaximumCapacity() &&
         survived_last_scavenge_ * 100 / new_space_.TotalCapacity() >= 10) {
       // Grow the size of new space if there is room to grow, and more than 10%
       // have survived the last scavenge.
       new_space_.Grow();
       survived_since_last_expansion_ = 0;
     }
   } else if (new_space_.TotalCapacity() < new_space_.MaximumCapacity() &&
              survived_since_last_expansion_ > new_space_.TotalCapacity()) {
     // Grow the size of new space if there is room to grow, and enough data
     // has survived scavenge since the last expansion.
     new_space_.Grow();
     survived_since_last_expansion_ = 0;
   }
+  }
 }
 
 
 static bool IsUnscavengedHeapObject(Heap* heap, Object** p) {
   return heap->InNewSpace(*p) &&
          !HeapObject::cast(*p)->map_word().IsForwardingAddress();
 }
 
 
 void Heap::ScavengeStoreBufferCallback(Heap* heap, MemoryChunk* page,
@@ skipping 3038 matching lines @@
   if (!IsHeapIterable()) {
     CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
   }
   if (mark_compact_collector()->sweeping_in_progress()) {
     mark_compact_collector()->EnsureSweepingCompleted();
   }
   DCHECK(IsHeapIterable());
 }
 
 
-bool Heap::HasLowAllocationRate(size_t allocation_rate) {
+bool Heap::HasLowAllocationRate() {
   static const size_t kLowAllocationRate = 1000;
+  size_t allocation_rate =
+      tracer()->CurrentAllocationThroughputInBytesPerMillisecond();
   if (allocation_rate == 0) return false;
   return allocation_rate < kLowAllocationRate;
 }
 
 
-void Heap::ReduceNewSpaceSize(size_t allocation_rate) {
-  if (!FLAG_predictable && HasLowAllocationRate(allocation_rate)) {
-    new_space_.Shrink();
-    UncommitFromSpace();
+bool Heap::HasLowYoungGenerationAllocationUtilization() {
+  const double low_mutator_utilization = 0.01;
+  double allocation_speed = static_cast<double>(
+      tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond());
+  double scavenging_speed =
+      static_cast<double>(tracer()->ScavengeSpeedInBytesPerMillisecond());
+  double mutator_utilization =
+      allocation_speed / (allocation_speed + scavenging_speed);
+  return mutator_utilization < low_mutator_utilization;
+}
+
+
+void Heap::ReduceNewSpaceSize() {
+  if (!FLAG_predictable) {
+    if (HasLowYoungGenerationAllocationUtilization()) {
+      new_space_.Shrink();
+    }
+    if (HasLowAllocationRate()) {
+      UncommitFromSpace();
+    }
   }
 }
 
 
 bool Heap::TryFinalizeIdleIncrementalMarking(
     double idle_time_in_ms, size_t size_of_objects,
     size_t final_incremental_mark_compact_speed_in_bytes_per_ms) {
   if (FLAG_overapproximate_weak_closure &&
       (incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
        (!incremental_marking()->weak_closure_was_overapproximated() &&
@@ skipping 36 matching lines @@
           tracer()->FinalIncrementalMarkCompactSpeedInBytesPerMillisecond());
   heap_state.scavenge_speed_in_bytes_per_ms =
       static_cast<size_t>(tracer()->ScavengeSpeedInBytesPerMillisecond());
   heap_state.used_new_space_size = new_space_.Size();
   heap_state.new_space_capacity = new_space_.Capacity();
   heap_state.new_space_allocation_throughput_in_bytes_per_ms =
       tracer()->NewSpaceAllocationThroughputInBytesPerMillisecond();
   heap_state.current_allocation_throughput_in_bytes_per_ms =
       tracer()->CurrentAllocationThroughputInBytesPerMillisecond();
   intptr_t limit = old_generation_allocation_limit_;
-  if (HasLowAllocationRate(
-          heap_state.current_allocation_throughput_in_bytes_per_ms)) {
+  if (HasLowAllocationRate()) {
     limit = idle_old_generation_allocation_limit_;
   }
   heap_state.can_start_incremental_marking =
       incremental_marking()->CanBeActivated() &&
       HeapIsFullEnoughToStartIncrementalMarking(limit) &&
       !mark_compact_collector()->sweeping_in_progress();
   return heap_state;
 }
 
 
@@ skipping 1962 matching lines @@
     *object_type = "CODE_TYPE";                                                \
     *object_sub_type = "CODE_AGE/" #name;                                      \
     return true;
     CODE_AGE_LIST_COMPLETE(COMPARE_AND_RETURN_NAME)
 #undef COMPARE_AND_RETURN_NAME
   }
   return false;
 }
 }  // namespace internal
 }  // namespace v8