Make the speed of incrmental marking depend also on the rate

src/spaces.h

 // Copyright 2011 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 266 matching lines @@
     CellPrinter printer;
     for (int i = 0; i < CellsCount(); i++) {
       printer.Print(i, cells()[i]);
     }
     printer.Flush();
     PrintF("\n");
   }
 
   bool IsClean() {
     for (int i = 0; i < CellsCount(); i++) {
-      if (cells()[i] != 0) return false;
+      if (cells()[i] != 0) {
+        return false;
+      }
     }
     return true;
   }
 };
 
 
 class SkipList;
 class SlotsBuffer;
 
 // MemoryChunk represents a memory region owned by a specific space.
@@ skipping 68 matching lines @@
     return addr >= area_start() && addr < area_end();
   }
 
   // Checks whether addr can be a limit of addresses in this page.
   // It's a limit if it's in the page, or if it's just after the
   // last byte of the page.
   bool ContainsLimit(Address addr) {
     return addr >= area_start() && addr <= area_end();
   }
 
+  // Every n write barrier invocations we go to runtime even though
+  // we could have handled it in generated code.  This lets us check
+  // whether we have hit the limit and should do some more marking.
+  static const int kWriteBarrierCounterGranularity = 500;
+
   enum MemoryChunkFlags {
     IS_EXECUTABLE,
     ABOUT_TO_BE_FREED,
     POINTERS_TO_HERE_ARE_INTERESTING,
     POINTERS_FROM_HERE_ARE_INTERESTING,
     SCAN_ON_SCAVENGE,
     IN_FROM_SPACE,  // Mutually exclusive with IN_TO_SPACE.
     IN_TO_SPACE,    // All pages in new space has one of these two set.
     NEW_SPACE_BELOW_AGE_MARK,
     CONTAINS_ONLY_DATA,
@@ skipping 75 matching lines @@
              live_byte_count_ + by);
     }
     live_byte_count_ += by;
     ASSERT_LE(static_cast<unsigned>(live_byte_count_), size_);
   }
   int LiveBytes() {
     ASSERT(static_cast<unsigned>(live_byte_count_) <= size_);
     return live_byte_count_;
   }
 
+  int write_barrier_counter() {
+    return static_cast<int>(write_barrier_counter_);
+  }
+
+  void set_write_barrier_counter(int counter) {
+    write_barrier_counter_ = counter;
+  }
+
+
   static void IncrementLiveBytesFromGC(Address address, int by) {
     MemoryChunk::FromAddress(address)->IncrementLiveBytes(by);
   }
 
   static void IncrementLiveBytesFromMutator(Address address, int by);
 
   static const intptr_t kAlignment =
       (static_cast<uintptr_t>(1) << kPageSizeBits);
 
   static const intptr_t kAlignmentMask = kAlignment - 1;
 
   static const intptr_t kSizeOffset = kPointerSize + kPointerSize;
 
   static const intptr_t kLiveBytesOffset =
      kSizeOffset + kPointerSize + kPointerSize + kPointerSize +
      kPointerSize + kPointerSize +
      kPointerSize + kPointerSize + kPointerSize + kIntSize;
 
   static const size_t kSlotsBufferOffset = kLiveBytesOffset + kIntSize;
 
-  static const size_t kHeaderSize =
+  static const size_t kWriteBarrierCounterOffset =
       kSlotsBufferOffset + kPointerSize + kPointerSize;
 
+  static const size_t kHeaderSize = kWriteBarrierCounterOffset + kPointerSize;
+
   static const int kBodyOffset =
     CODE_POINTER_ALIGN(MAP_POINTER_ALIGN(kHeaderSize + Bitmap::kSize));
 
   // The start offset of the object area in a page. Aligned to both maps and
   // code alignment to be suitable for both.  Also aligned to 32 words because
   // the marking bitmap is arranged in 32 bit chunks.
   static const int kObjectStartAlignment = 32 * kPointerSize;
   static const int kObjectStartOffset = kBodyOffset - 1 +
       (kObjectStartAlignment - (kBodyOffset - 1) % kObjectStartAlignment);
 
@@ skipping 114 matching lines @@
   // in a fixed array.
   Address owner_;
   Heap* heap_;
   // Used by the store buffer to keep track of which pages to mark scan-on-
   // scavenge.
   int store_buffer_counter_;
   // Count of bytes marked black on page.
   int live_byte_count_;
   SlotsBuffer* slots_buffer_;
   SkipList* skip_list_;
+  intptr_t write_barrier_counter_;
 
   static MemoryChunk* Initialize(Heap* heap,
                                  Address base,
                                  size_t size,
                                  Address area_start,
                                  Address area_end,
                                  Executability executable,
                                  Space* owner);
 
   friend class MemoryAllocator;
@@ skipping 2011 matching lines @@
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_SPACES_H_