Change halfway-to-the-max GC trigger to measure committed pages, not allocated objects

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 1079 matching lines @@
 
   inline intptr_t OldGenerationCapacityAvailable() {
     return max_old_generation_size_ - PromotedTotalSize();
   }
 
   static const intptr_t kMinimumOldGenerationAllocationLimit =
       8 * (Page::kPageSize > MB ? Page::kPageSize : MB);
 
   static const int kInitalOldGenerationLimitFactor = 2;
 
+  static const intptr_t kDefaultMaxOldGenSize = 700ul * (kPointerSize / 4) * MB;
+
 #if V8_OS_ANDROID
   // Don't apply pointer multiplier on Android since it has no swap space and
   // should instead adapt it's heap size based on available physical memory.
   static const int kPointerMultiplier = 1;
 #else
   static const int kPointerMultiplier = i::kPointerSize / 4;
 #endif
 
   // The new space size has to be a power of 2. Sizes are in MB.
   static const int kMaxSemiSpaceSizeLowMemoryDevice = 1 * kPointerMultiplier;
@@ skipping 12 matching lines @@
   // The executable size has to be a multiple of Page::kPageSize.
   // Sizes are in MB.
   static const int kMaxExecutableSizeLowMemoryDevice = 96 * kPointerMultiplier;
   static const int kMaxExecutableSizeMediumMemoryDevice =
       192 * kPointerMultiplier;
   static const int kMaxExecutableSizeHighMemoryDevice =
       256 * kPointerMultiplier;
   static const int kMaxExecutableSizeHugeMemoryDevice =
       256 * kPointerMultiplier;
 
-  intptr_t OldGenerationAllocationLimit(intptr_t old_gen_size,
-                                        int freed_global_handles);
+  void SetOldGenerationAllocationLimit(intptr_t old_gen_size,
+                                       int freed_global_handles,
+                                       bool weak_callbacks_completed);
 
   // Indicates whether inline bump-pointer allocation has been disabled.
   bool inline_allocation_disabled() { return inline_allocation_disabled_; }
 
   // Switch whether inline bump-pointer allocation should be used.
   void EnableInlineAllocation();
   void DisableInlineAllocation();
 
   // Implements the corresponding V8 API function.
   bool IdleNotification(double deadline_in_seconds);
@@ skipping 93 matching lines @@
   }
 
   inline bool NextGCIsLikelyToBeFull() {
     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 (PromotedTotalSize() >= adjusted_allocation_limit) return true;
+    if (PromotedTotalSize() >= adjusted_allocation_limit) {
+      if (FLAG_trace_gc_verbose) {
+        PrintF("Next GC likely to be full: We are at %" V8_PTR_PREFIX
+               "dMbytes out of %" V8_PTR_PREFIX "dMbytes\n",
+               PromotedTotalSize() >> 20,
+               old_generation_allocation_limit_ >> 20);
+      }
+      return true;
+    }
+
+    if (CommittedOldGenerationMemory() >=
+        old_generation_committed_memory_limit_) {
+      if (FLAG_trace_gc_verbose) {
+        PrintF("Next GC likely to be full: We are at %" V8_PTR_PREFIX
+               "dMbytes committed out of %" V8_PTR_PREFIX "dMbytes\n",
+               CommittedOldGenerationMemory() >> 20,
+               old_generation_committed_memory_limit_ >> 20);
+      }
+      return true;
+    }
 
     return false;
   }
 
   void UpdateNewSpaceReferencesInExternalStringTable(
       ExternalStringTableUpdaterCallback updater_func);
 
   void UpdateReferencesInExternalStringTable(
       ExternalStringTableUpdaterCallback updater_func);
 
@@ skipping 58 matching lines @@
   // Returns the current sweep generation.
   int sweep_generation() { return sweep_generation_; }
 
   bool concurrent_sweeping_enabled() { return concurrent_sweeping_enabled_; }
 
   inline Isolate* isolate();
 
   void CallGCPrologueCallbacks(GCType gc_type, GCCallbackFlags flags);
   void CallGCEpilogueCallbacks(GCType gc_type, GCCallbackFlags flags);
 
   inline bool OldGenerationAllocationLimitReached();

[ulan, 2015/03/26 08:28:55]

To be consistent, we need similar predicate for committed_memory_limit and check
it at every place we expand old space.

 
   inline void DoScavengeObject(Map* map, HeapObject** slot, HeapObject* obj) {
     scavenging_visitors_table_.GetVisitor(map)(map, slot, obj);
   }
 
   void QueueMemoryChunkForFree(MemoryChunk* chunk);
   void FreeQueuedChunks();
 
   int gc_count() const { return gc_count_; }
 
@@ skipping 291 matching lines @@
 #ifdef DEBUG
   // If the --gc-interval flag is set to a positive value, this
   // variable holds the value indicating the number of allocations
   // 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.
+  // generation and on every allocation in large object space. This only
+  // measures objects, so it may be underreporting if we have fragmentation.
   intptr_t old_generation_allocation_limit_;
 
+  // As above, but counts pages, not objects, so is more likely to trigger
+  // when we have fragmentation.
+  intptr_t old_generation_committed_memory_limit_;
+
   // 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 412 matching lines @@
   void ConfigureInitialOldGenerationSize();
 
   void SelectScavengingVisitorsTable();
 
   void IdleMarkCompact(const char* message);
 
   bool TryFinalizeIdleIncrementalMarking(
       double idle_time_in_ms, size_t size_of_objects,
       size_t mark_compact_speed_in_bytes_per_ms);
 
-  bool WorthActivatingIncrementalMarking();
-
   void ClearObjectStats(bool clear_last_time_stats = false);
 
   inline void UpdateAllocationsHash(HeapObject* object);
   inline void UpdateAllocationsHash(uint32_t value);
   inline void PrintAlloctionsHash();
 
   // Object counts and used memory by InstanceType
   size_t object_counts_[OBJECT_STATS_COUNT];
   size_t object_counts_last_time_[OBJECT_STATS_COUNT];
   size_t object_sizes_[OBJECT_STATS_COUNT];
@@ skipping 533 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_