After performing scavenge, hint OS that data in from spaces are no more neede...

src/heap.cc

 // Copyright 2009 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 775 matching lines @@
       target->Iterate(&scavenge_visitor);
       UpdateRSet(target);
     }
 
     // Take another spin if there are now unswept objects in new space
     // (there are currently no more unswept promoted objects).
   } while (new_space_front < new_space_.top());
 
   // Set age mark.
   new_space_.set_age_mark(new_space_.top());
+  new_space_.ResetFromSpace();
 
   // Update how much has survived scavenge.
   survived_since_last_expansion_ +=
       (PromotedSpaceSize() - survived_watermark) + new_space_.Size();
 
   LOG(ResourceEvent("scavenge", "end"));
 
   gc_state_ = NOT_IN_GC;
 }
 
@@ skipping 3242 matching lines @@
   for (int i = 0; i < kNumberOfCaches; i++) {
     if (caches_[i] != NULL) {
       delete caches_[i];
       caches_[i] = NULL;
     }
   }
 }
 
 
 } }  // namespace v8::internal