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

src/platform.h

 // Copyright 2006-2008 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 278 matching lines @@
 
   // Returns the size of the reserved memory.
   size_t size() { return size_; }
 
   // Commits real memory. Returns whether the operation succeeded.
   bool Commit(void* address, size_t size, bool is_executable);
 
   // Uncommit real memory.  Returns whether the operation succeeded.
   bool Uncommit(void* address, size_t size);
 
+  // Give OS a hint that data of that span could be just discarded
+  // (no need to page it out).  Might be implemented as noop.
+  bool Reset(void* address, size_t size, bool is_executable);
+
  private:
   void* address_;  // Start address of the virtual memory.
   size_t size_;  // Size of the virtual memory.
 };
 
 
 // ----------------------------------------------------------------------------
 // ThreadHandle
 //
 // A ThreadHandle represents a thread identifier for a thread. The ThreadHandle
@@ skipping 238 matching lines @@
   bool active_;
   PlatformData* data_;  // Platform specific data.
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_