Don't unlink evacuation candidates before sweeping, move them to the end of their list of pages.

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 1836 matching lines @@
     SetTopAndLimit(NULL, NULL);
   }
 
   void Allocate(int bytes) {
     accounting_stats_.AllocateBytes(bytes);
   }
 
   void IncreaseCapacity(int size);
 
   // Releases an unused page and shrinks the space.
-  void ReleasePage(Page* page, bool unlink);
+  void ReleasePage(Page* page);
 
   // The dummy page that anchors the linked list of pages.
   Page* anchor() { return &anchor_; }
 
 #ifdef VERIFY_HEAP
   // Verify integrity of this space.
   virtual void Verify(ObjectVisitor* visitor);
 
   // Overridden by subclasses to verify space-specific object
   // properties (e.g., only maps or free-list nodes are in map space).
@@ skipping 45 matching lines @@
   void ResetUnsweptFreeBytes() {
     unswept_free_bytes_ = 0;
   }
 
   // This function tries to steal size_in_bytes memory from the sweeper threads
   // free-lists. If it does not succeed stealing enough memory, it will wait
   // for the sweeper threads to finish sweeping.
   // It returns true when sweeping is completed and false otherwise.
   bool EnsureSweeperProgress(intptr_t size_in_bytes);
 
+  void set_end_of_unswept_pages(Page* page) {
+    end_of_unswept_pages_ = page;
+  }
+
+  Page* end_of_unswept_pages() {
+    return end_of_unswept_pages_;
+  }
+
   Page* FirstPage() { return anchor_.next_page(); }
   Page* LastPage() { return anchor_.prev_page(); }
 
   void EvictEvacuationCandidatesFromFreeLists();
 
   bool CanExpand();
 
   // Returns the number of total pages in this space.
   int CountTotalPages();
 
@@ skipping 24 matching lines @@
   // Normal allocation information.
   AllocationInfo allocation_info_;
 
   bool was_swept_conservatively_;
 
   // The number of free bytes which could be reclaimed by advancing the
   // concurrent sweeper threads.  This is only an estimation because concurrent
   // sweeping is done conservatively.
   intptr_t unswept_free_bytes_;
 
+  Page* end_of_unswept_pages_;
+
   // Expands the space by allocating a fixed number of pages. Returns false if
   // it cannot allocate requested number of pages from OS, or if the hard heap
   // size limit has been hit.
   bool Expand();
 
   // Generic fast case allocation function that tries linear allocation at the
   // address denoted by top in allocation_info_.
   inline HeapObject* AllocateLinearly(int size_in_bytes);
 
   // Slow path of AllocateRaw.  This function is space-dependent.
@@ skipping 989 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_