Simplifying GC heuristics, deleted old generation allocation limit.

src/heap.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1543 matching lines @@
   }
 
   inline Address* NewSpaceHighPromotionModeActiveAddress() {
     return reinterpret_cast<Address*>(&new_space_high_promotion_mode_active_);
   }
 
   inline intptr_t PromotedTotalSize() {
     return PromotedSpaceSizeOfObjects() + PromotedExternalMemorySize();
   }
 
-  // True if we have reached the allocation limit in the old generation that
-  // should force the next GC (caused normally) to be a full one.
-  inline bool OldGenerationPromotionLimitReached() {
-    return PromotedTotalSize() > old_gen_promotion_limit_;
-  }
-
   inline intptr_t OldGenerationSpaceAvailable() {
-    return old_gen_allocation_limit_ - PromotedTotalSize();
+    return old_generation_allocation_limit_ - PromotedTotalSize();
   }
 
   inline intptr_t OldGenerationCapacityAvailable() {
     return max_old_generation_size_ - PromotedTotalSize();
   }
 
-  static const intptr_t kMinimumPromotionLimit = 5 * Page::kPageSize;
-  static const intptr_t kMinimumAllocationLimit =
+  static const intptr_t kMinimumOldGenerationAllocationLimit =
       8 * (Page::kPageSize > MB ? Page::kPageSize : MB);
 
-  intptr_t OldGenPromotionLimit(intptr_t old_gen_size) {
+  intptr_t OldGenerationAllocationLimit(intptr_t old_gen_size) {
     const int divisor = FLAG_stress_compaction ? 10 :
         new_space_high_promotion_mode_active_ ? 1 : 3;
     intptr_t limit =
-        Max(old_gen_size + old_gen_size / divisor, kMinimumPromotionLimit);
+        Max(old_gen_size + old_gen_size / divisor,
+            kMinimumOldGenerationAllocationLimit);
     limit += new_space_.Capacity();
     // TODO(hpayer): Can be removed when when pretenuring is supported for all
     // allocation sites.
-    if (IsHighSurvivalRate() && IsStableOrIncreasingSurvivalTrend()) {
-      limit *= 2;
-    }
-    intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
-    return Min(limit, halfway_to_the_max);
-  }
-
-  intptr_t OldGenAllocationLimit(intptr_t old_gen_size) {
-    const int divisor = FLAG_stress_compaction ? 8 :
-        new_space_high_promotion_mode_active_ ? 1 : 2;
-    intptr_t limit =
-        Max(old_gen_size + old_gen_size / divisor, kMinimumAllocationLimit);
-    limit += new_space_.Capacity();
-    // TODO(hpayer): Can be removed when when pretenuring is supported for all
-    // allocation sites.
     if (IsHighSurvivalRate() && IsStableOrIncreasingSurvivalTrend()) {
       limit *= 2;
     }
     intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
     return Min(limit, halfway_to_the_max);
   }
 
   // Implements the corresponding V8 API function.
   bool IdleNotification(int hint);
 
@@ skipping 57 matching lines @@
     ASSERT(survived >= 0);
     young_survivors_after_last_gc_ = survived;
     survived_since_last_expansion_ += survived;
   }
 
   inline bool NextGCIsLikelyToBeFull() {
     if (FLAG_gc_global) return true;
 
     if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true;
 
-    intptr_t total_promoted = PromotedTotalSize();
+    intptr_t adjusted_allocation_limit =
+        old_generation_allocation_limit_ - new_space_.Capacity();
 
-    intptr_t adjusted_promotion_limit =
-        old_gen_promotion_limit_ - new_space_.Capacity();
-
-    if (total_promoted >= adjusted_promotion_limit) return true;
-
-    intptr_t adjusted_allocation_limit =
-        old_gen_allocation_limit_ - new_space_.Capacity() / 5;
-
-    if (PromotedSpaceSizeOfObjects() >= adjusted_allocation_limit) return true;
+    if (PromotedTotalSize() >= adjusted_allocation_limit) return true;
 
     return false;
   }
 
-
   void UpdateNewSpaceReferencesInExternalStringTable(
       ExternalStringTableUpdaterCallback updater_func);
 
   void UpdateReferencesInExternalStringTable(
       ExternalStringTableUpdaterCallback updater_func);
 
   void ProcessWeakReferences(WeakObjectRetainer* retainer);
 
   void VisitExternalResources(v8::ExternalResourceVisitor* visitor);
 
@@ skipping 304 matching lines @@
   bool disallow_allocation_failure_;
 #endif  // DEBUG
 
   // Indicates that the new space should be kept small due to high promotion
   // rates caused by the mutator allocating a lot of long-lived objects.
   // TODO(hpayer): change to bool if no longer accessed from generated code
   intptr_t new_space_high_promotion_mode_active_;
 
   // 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.
-  intptr_t old_gen_promotion_limit_;
-
-  // Limit that triggers a global GC as soon as is reasonable.  This is
-  // checked before expanding a paged space in the old generation and on
-  // every allocation in large object space.
-  intptr_t old_gen_allocation_limit_;
+  // 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_;
 
   // Used to adjust the limits that control the timing of the next GC.
   intptr_t size_of_old_gen_at_last_old_space_gc_;
 
   // Limit on the amount of externally allocated memory allowed
   // between global GCs. If reached a global GC is forced.
   intptr_t external_allocation_limit_;
 
   // The amount of external memory registered through the API kept alive
   // by global handles
   intptr_t amount_of_external_allocated_memory_;
 
   // Caches the amount of external memory registered at the last global gc.
   intptr_t amount_of_external_allocated_memory_at_last_global_gc_;
 
   // Indicates that an allocation has failed in the old generation since the
   // last GC.
-  int old_gen_exhausted_;
+  bool old_gen_exhausted_;
 
   Object* native_contexts_list_;
 
   StoreBufferRebuilder store_buffer_rebuilder_;
 
   struct StringTypeTable {
     InstanceType type;
     int size;
     RootListIndex index;
   };
@@ skipping 1050 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_