Uncommit and shrink semi-spaces only on low allocation rate.

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 4547 matching lines @@
   if (!IsHeapIterable()) {
     CollectAllGarbage(kMakeHeapIterableMask, "Heap::MakeHeapIterable");
   }
   if (mark_compact_collector()->sweeping_in_progress()) {
     mark_compact_collector()->EnsureSweepingCompleted();
   }
   DCHECK(IsHeapIterable());
 }
 
 
-void Heap::ReduceNewSpaceSize(GCIdleTimeAction action) {
-  if (action.reduce_memory &&
+bool Heap::HasLowAllocationRate(GCIdleTimeHandler::HeapState heap_state) {
+  static const size_t kLowAllocationRate = 1000;
+  return heap_state.current_new_space_allocation_throughput_in_bytes_per_ms <

[ulan, 2015/05/21 15:21:25]

check for heap_state.current_new_space_allocation_throughput_in_bytes_per_ms ==
0 and be conservative in that case?

[Hannes Payer (out of office), 2015/05/21 17:17:03]

Good point! Done.

+         kLowAllocationRate;
+}
+
+
+void Heap::ReduceNewSpaceSize(GCIdleTimeAction action,
+                              GCIdleTimeHandler::HeapState heap_state) {
+  if (HasLowAllocationRate(heap_state) &&
       (action.type == DO_SCAVENGE || action.type == DO_FULL_GC ||
        (action.type == DO_INCREMENTAL_MARKING &&
         incremental_marking()->IsStopped()))) {
     new_space_.Shrink();
     UncommitFromSpace();
   }
 }
 
 
 bool Heap::TryFinalizeIdleIncrementalMarking(
@@ skipping 48 matching lines @@
       tracer()->IncrementalMarkingSpeedInBytesPerMillisecond());
   heap_state.final_incremental_mark_compact_speed_in_bytes_per_ms =
       static_cast<size_t>(
           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_new_space_allocation_throughput_in_bytes_per_ms =
+      tracer()->CurrentNewSpaceAllocationThroughputInBytesPerMillisecond();
   return heap_state;
 }
 
 
 bool Heap::PerformIdleTimeAction(GCIdleTimeAction action,
                                  GCIdleTimeHandler::HeapState heap_state,
                                  double deadline_in_ms,
                                  bool is_long_idle_notification) {
   bool result = false;
   switch (action.type) {
@@ skipping 42 matching lines @@
     case DO_SCAVENGE:
       CollectGarbage(NEW_SPACE, "idle notification: scavenge");
       break;
     case DO_FINALIZE_SWEEPING:
       mark_compact_collector()->EnsureSweepingCompleted();
       break;
     case DO_NOTHING:
       break;
   }
 
-  ReduceNewSpaceSize(action);
+  ReduceNewSpaceSize(action, heap_state);
   return result;
 }
 
 
 void Heap::IdleNotificationEpilogue(GCIdleTimeAction action,
                                     GCIdleTimeHandler::HeapState heap_state,
                                     double start_ms, double deadline_in_ms,
                                     bool is_long_idle_notification) {
   double idle_time_in_ms = deadline_in_ms - start_ms;
   double current_time = MonotonicallyIncreasingTimeInMs();
@@ skipping 1876 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 v8::internal