Use smaller heap growing factor in idle notification to start incremental marking when there is idl…

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 "src/allocation.h"
@@ skipping 1207 matching lines @@
   inline void IncrementNodesCopiedInNewSpace() { nodes_copied_in_new_space_++; }
 
   inline void IncrementNodesPromoted() { nodes_promoted_++; }
 
   inline void IncrementYoungSurvivorsCounter(int survived) {
     DCHECK(survived >= 0);
     survived_last_scavenge_ = survived;
     survived_since_last_expansion_ += survived;
   }
 
-  inline bool NextGCIsLikelyToBeFull() {
+  inline bool NextGCIsLikelyToBeFull(intptr_t limit = 0) {

[ulan, 2015/04/16 14:17:22]

Always pass the limit (either the old_generation_allocation_limit_ or the
idle_limit) and get rid of the conditional below?

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

     if (FLAG_gc_global) return true;
 
     if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true;
 
-    intptr_t adjusted_allocation_limit =
-        old_generation_allocation_limit_ - new_space_.Capacity();
+    if (limit == 0) limit = old_generation_allocation_limit_;
+    intptr_t adjusted_allocation_limit = limit - new_space_.Capacity();
 
     if (PromotedTotalSize() >= adjusted_allocation_limit) return true;
 
     return false;
   }
 
   void UpdateNewSpaceReferencesInExternalStringTable(
       ExternalStringTableUpdaterCallback updater_func);
 
   void UpdateReferencesInExternalStringTable(
@@ skipping 381 matching lines @@
   // remain until the next failure and garbage collection.
   int allocation_timeout_;
 #endif  // DEBUG
 
   // Limit that triggers a global GC on the next (normally caused) GC.  This
   // is checked when we have already decided to do a GC to help determine
   // which collector to invoke, before expanding a paged space in the old
   // generation and on every allocation in large object space.
   intptr_t old_generation_allocation_limit_;
 
+  // The minimum factor used to grow the old generation.

[ulan, 2015/04/16 14:17:22]

Each additional state variable complicates GC scheduling. Let's minimize the
number of state variables.

One state variable is unavoidable: either current_old_generation_growing_factor_
or better idle_limit_.

Everything else should be a (local) constant I think.

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

+  double min_old_generation_growing_factor_;

[Erik Corry Chromium.org, 2015/04/16 14:16:44]

This never changes.

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

+
+  // The maximum factor used to grow the old generation.
+  double max_old_generation_growing_factor_;
+
+  // The factor used in the idle notification to grow the old generation.
+  double idle_old_generation_growing_factor_;

[Erik Corry Chromium.org, 2015/04/16 14:16:44]

This never changes.

I think it keeps things simpler to have these as genuine constants.

[Hannes Payer (out of office), 2015/04/16 14:46:45]

Done.

+
+  // The currently used old generation growing factor determined by the heap
+  // growing strategy (not by the idle notification).
+  double current_old_generation_growing_factor_;
+
   // Indicates that an allocation has failed in the old generation since the
   // last GC.
   bool old_gen_exhausted_;
 
   // Indicates that inline bump-pointer allocation has been globally disabled
   // for all spaces. This is used to disable allocations in generated code.
   bool inline_allocation_disabled_;
 
   // Weak list heads, threaded through the objects.
   // List heads are initialized lazily and contain the undefined_value at start.
@@ skipping 960 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_