Dampen old generation allocation limit after scavenge if allocation rate is low.

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 1265 matching lines @@
     freed_global_handles =
         isolate_->global_handles()->PostGarbageCollectionProcessing(collector);
   }
   gc_post_processing_depth_--;
 
   isolate_->eternal_handles()->PostGarbageCollectionProcessing(this);
 
   // Update relocatables.
   Relocatable::PostGarbageCollectionProcessing(isolate_);
 
+  double gc_speed = tracer()->CombinedMarkCompactSpeedInBytesPerMillisecond();
+  double mutator_speed = static_cast<double>(
+      tracer()
+          ->CurrentOldGenerationAllocationThroughputInBytesPerMillisecond());
+  intptr_t old_gen_size = PromotedSpaceSizeOfObjects();
   if (collector == MARK_COMPACTOR) {
     // Register the amount of external allocated memory.
     amount_of_external_allocated_memory_at_last_global_gc_ =
         amount_of_external_allocated_memory_;
-    double gc_speed = tracer()->CombinedMarkCompactSpeedInBytesPerMillisecond();
-    double mutator_speed = static_cast<double>(
-        tracer()
-            ->CurrentOldGenerationAllocationThroughputInBytesPerMillisecond());
-    intptr_t old_gen_size = PromotedSpaceSizeOfObjects();
     SetOldGenerationAllocationLimit(old_gen_size, gc_speed, mutator_speed);
+  } else if (HasLowYoungGenerationAllocationRate()) {
+    DampenOldGenerationAllocationLimit(old_gen_size, gc_speed, mutator_speed);
   }
 
   {
     GCCallbacksScope scope(this);
     if (scope.CheckReenter()) {
       AllowHeapAllocation allow_allocation;
       GCTracer::Scope scope(tracer(), GCTracer::Scope::EXTERNAL);
       VMState<EXTERNAL> state(isolate_);
       HandleScope handle_scope(isolate_);
       CallGCEpilogueCallbacks(gc_type, gc_callback_flags);
@@ skipping 4262 matching lines @@
     PrintIsolate(
         isolate_,
         "Grow: old size: %" V8_PTR_PREFIX "d KB, new limit: %" V8_PTR_PREFIX
         "d KB (%.1f), new idle limit: %" V8_PTR_PREFIX "d KB (%.1f)\n",
         old_gen_size / KB, old_generation_allocation_limit_ / KB, factor,
         idle_old_generation_allocation_limit_ / KB, idle_factor);
   }
 }
 
 
+void Heap::DampenOldGenerationAllocationLimit(intptr_t old_gen_size,
+                                              double gc_speed,
+                                              double mutator_speed) {
+  double factor = HeapGrowingFactor(gc_speed, mutator_speed);
+  intptr_t limit = CalculateOldGenerationAllocationLimit(factor, old_gen_size);
+  if (limit < old_generation_allocation_limit_) {
+    if (FLAG_trace_gc_verbose) {
+      PrintIsolate(isolate_, "Dampen: old size: %" V8_PTR_PREFIX
+                             "d KB, old limit: %" V8_PTR_PREFIX "d KB, \n",
+                   "new limit: %" V8_PTR_PREFIX "d KB (%.1f)\n",
+                   old_gen_size / KB, old_generation_allocation_limit_ / KB,
+                   limit / KB, factor);
+    }
+    old_generation_allocation_limit_ = limit;
+  }
+}
+
+
 void Heap::EnableInlineAllocation() {
   if (!inline_allocation_disabled_) return;
   inline_allocation_disabled_ = false;
 
   // Update inline allocation limit for new space.
   new_space()->UpdateInlineAllocationLimit(0);
 }
 
 
 void Heap::DisableInlineAllocation() {
@@ skipping 1199 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