Add flag to trace the amount of external memory.

R=yangguo@chromium.org

Review URL: https://chromiumcodereview.appspot.com/10824196

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12269 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/flag-definitions.h

@@ -370,6 +370,9 @@ DEFINE_bool(trace_gc_verbose, false,
             "print more details following each garbage collection")
 DEFINE_bool(trace_fragmentation, false,
             "report fragmentation for old pointer and data pages")
+DEFINE_bool(trace_external_memory, false,
+            "print amount of external allocated memory after each time "
+            "it is adjusted.")
 DEFINE_bool(collect_maps, true,
             "garbage collect maps from which no objects can be reached")
 DEFINE_bool(flush_code, true,

src/heap-inl.h

@@ -487,6 +487,13 @@ intptr_t Heap::AdjustAmountOfExternalAllocatedMemory(
       amount_of_external_allocated_memory_at_last_global_gc_ = 0;
     }
   }
+  if (FLAG_trace_external_memory) {
+    PrintPID("%8.0f ms: ", isolate()->time_millis_since_init());
+    PrintF("Adjust amount of external memory: delta=%6" V8_PTR_PREFIX "d KB, "
+           " amount=%6" V8_PTR_PREFIX "d KB, isolate=0x%08" V8PRIxPTR ".\n",
+           change_in_bytes / 1024, amount_of_external_allocated_memory_ / 1024,
+           reinterpret_cast<intptr_t>(isolate()));
+  }
   ASSERT(amount_of_external_allocated_memory_ >= 0);
   return amount_of_external_allocated_memory_;
 }