- Introduce histograms collecting data about the number of set remembered set...

src/spaces.cc

 // 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 2404 matching lines @@
       int extra_rset_bytes = ExtraRSetBytesFor(size);
       memset(object->address() + size, 0, extra_rset_bytes);
     }
   }
 }
 
 
 void LargeObjectSpace::IterateRSet(ObjectSlotCallback copy_object_func) {
   ASSERT(Page::is_rset_in_use());
 
+  static void* lo_rset_histogram = StatsTable::CreateHistogram(
+      "V8.RSet_LO",
+      0,
+      // Keeping this histogram's buckets the same as the paged space histogram.
+      Page::kObjectAreaSize / kPointerSize,
+      30);
+  
   LargeObjectIterator it(this);
   while (it.has_next()) {
     // We only have code, sequential strings, or fixed arrays in large
     // object space, and only fixed arrays can possibly contain pointers to
     // the young generation.
     HeapObject* object = it.next();
     if (object->IsFixedArray()) {
       // Iterate the normal page remembered set range.
       Page* page = Page::FromAddress(object->address());
       Address object_end = object->address() + object->Size();
-      Heap::IterateRSetRange(page->ObjectAreaStart(),
-                             Min(page->ObjectAreaEnd(), object_end),
-                             page->RSetStart(),
-                             copy_object_func);
+      int count = Heap::IterateRSetRange(page->ObjectAreaStart(),
+                                         Min(page->ObjectAreaEnd(), object_end),
+                                         page->RSetStart(),
+                                         copy_object_func);
 
       // Iterate the extra array elements.
       if (object_end > page->ObjectAreaEnd()) {
-        Heap::IterateRSetRange(page->ObjectAreaEnd(), object_end,
-                               object_end, copy_object_func);
+        count += Heap::IterateRSetRange(page->ObjectAreaEnd(), object_end,
+                                        object_end, copy_object_func);
+      }
+      if (lo_rset_histogram != NULL) {
+        StatsTable::AddHistogramSample(lo_rset_histogram, count);
       }
     }
   }
 }
 
 
 void LargeObjectSpace::FreeUnmarkedObjects() {
   LargeObjectChunk* previous = NULL;
   LargeObjectChunk* current = first_chunk_;
   while (current != NULL) {
@@ skipping 153 matching lines @@
                      reinterpret_cast<Object**>(object->address()
                                                 + Page::kObjectAreaSize),
                      allocation_top);
       PrintF("\n");
     }
   }
 }
 #endif  // DEBUG
 
 } }  // namespace v8::internal