[heap] Do not use the high memory watermark for committed memory accounting in large object space.

src/heap/spaces.cc

 // 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.
 
 #include "src/heap/spaces.h"
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/base/platform/semaphore.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 2970 matching lines @@
     reinterpret_cast<Object**>(object->address())[1] = Smi::FromInt(0);
   }
 
   heap()->incremental_marking()->OldSpaceStep(object_size);
   AllocationStep(object->address(), object_size);
   return object;
 }
 
 
 size_t LargeObjectSpace::CommittedPhysicalMemory() {
-  if (!base::VirtualMemory::HasLazyCommits()) return CommittedMemory();
-  size_t size = 0;
-  LargePage* current = first_page_;
-  while (current != NULL) {
-    size += current->CommittedPhysicalMemory();
-    current = current->next_page();
-  }
-  return size;
+  // On a platform that provides lazy committing of memory, we over-account
+  // the actually committed memory. There is no easy way right now to support
+  // precise accounting of committed memory in large object space.
+  return CommittedMemory();
 }
 
 
 // GC support
 Object* LargeObjectSpace::FindObject(Address a) {
   LargePage* page = FindPage(a);
   if (page != NULL) {
     return page->GetObject();
   }
   return Smi::FromInt(0);  // Signaling not found.
@@ skipping 193 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8