New algorithm for selecting evacuation candidates

src/heap/spaces.h

 // Copyright 2011 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_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
@@ skipping 660 matching lines @@
   // Used by the incremental marker to keep track of the scanning progress in
   // large objects that have a progress bar and are scanned in increments.
   int progress_bar_;
   // Assuming the initial allocation on a page is sequential,
   // count highest number of bytes ever allocated on the page.
   int high_water_mark_;
 
   base::AtomicWord parallel_sweeping_;
 
   // PagedSpace free-list statistics.
-  intptr_t available_in_small_free_list_;
-  intptr_t available_in_medium_free_list_;
-  intptr_t available_in_large_free_list_;
-  intptr_t available_in_huge_free_list_;
-  intptr_t non_available_small_blocks_;
+  int available_in_small_free_list_;

[Hannes Payer (out of office), 2015/05/27 08:49:30]

Why int? What about size_t?

[ulan, 2015/05/27 11:33:20]

All free list counters in other places are signed. I changed it from intptr_t to
int because we don't need 64-bits to count free bytes in a page.

[Hannes Payer (out of office), 2015/05/27 12:41:34]

yeah...

+  int available_in_medium_free_list_;
+  int available_in_large_free_list_;
+  int available_in_huge_free_list_;
+  int non_available_small_blocks_;
 
   static MemoryChunk* Initialize(Heap* heap, Address base, size_t size,
                                  Address area_start, Address area_end,
                                  Executability executable, Space* owner);
 
  private:
   // next_chunk_ holds a pointer of type MemoryChunk
   base::AtomicWord next_chunk_;
   // prev_chunk_ holds a pointer of type MemoryChunk
   base::AtomicWord prev_chunk_;
@@ skipping 73 matching lines @@
                                  Executability executable, PagedSpace* owner);
 
   void InitializeAsAnchor(PagedSpace* owner);
 
   bool WasSwept() { return IsFlagSet(WAS_SWEPT); }
   void SetWasSwept() { SetFlag(WAS_SWEPT); }
   void ClearWasSwept() { ClearFlag(WAS_SWEPT); }
 
   void ResetFreeListStatistics();
 
+  int LiveBytesFromFreeList() {
+    return area_size() - non_available_small_blocks_ -
+           available_in_small_free_list_ - available_in_medium_free_list_ -
+           available_in_large_free_list_ - available_in_huge_free_list_;
+  }
+
 #define FRAGMENTATION_STATS_ACCESSORS(type, name) \
   type name() { return name##_; }                 \
   void set_##name(type name) { name##_ = name; }  \
   void add_##name(type name) { name##_ += name; }
 
-  FRAGMENTATION_STATS_ACCESSORS(intptr_t, non_available_small_blocks)
-  FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_small_free_list)
-  FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_medium_free_list)
-  FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_large_free_list)
-  FRAGMENTATION_STATS_ACCESSORS(intptr_t, available_in_huge_free_list)
+  FRAGMENTATION_STATS_ACCESSORS(int, non_available_small_blocks)
+  FRAGMENTATION_STATS_ACCESSORS(int, available_in_small_free_list)
+  FRAGMENTATION_STATS_ACCESSORS(int, available_in_medium_free_list)
+  FRAGMENTATION_STATS_ACCESSORS(int, available_in_large_free_list)
+  FRAGMENTATION_STATS_ACCESSORS(int, available_in_huge_free_list)
 
 #undef FRAGMENTATION_STATS_ACCESSORS
 
 #ifdef DEBUG
   void Print();
 #endif  // DEBUG
 
   friend class MemoryAllocator;
 };
 
@@ skipping 894 matching lines @@
   // Total amount of memory committed for this space.  For paged
   // spaces this equals the capacity.
   intptr_t CommittedMemory() override { return Capacity(); }
 
   // The maximum amount of memory ever committed for this space.
   intptr_t MaximumCommittedMemory() { return accounting_stats_.MaxCapacity(); }
 
   // Approximate amount of physical memory committed for this space.
   size_t CommittedPhysicalMemory() override;
 
-  struct SizeStats {
-    intptr_t Total() {
-      return small_size_ + medium_size_ + large_size_ + huge_size_;
-    }
-
-    intptr_t small_size_;
-    intptr_t medium_size_;
-    intptr_t large_size_;
-    intptr_t huge_size_;
-  };
-
-  void ObtainFreeListStatistics(Page* p, SizeStats* sizes);
   void ResetFreeListStatistics();
 
   // Sets the capacity, the available space and the wasted space to zero.
   // The stats are rebuilt during sweeping by adding each page to the
   // capacity and the size when it is encountered.  As free spaces are
   // discovered during the sweeping they are subtracted from the size and added
   // to the available and wasted totals.
   void ClearStats() {
     accounting_stats_.ClearSizeWaste();
     ResetFreeListStatistics();
@@ skipping 1165 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_SPACES_H_