Make new space allocation throughput estimation more accurate.

src/heap/spaces.h

 // 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.
 
 #ifndef V8_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
@@ skipping 2417 matching lines @@
     return to_space_.MaximumCommittedMemory() +
            from_space_.MaximumCommittedMemory();
   }
 
   // Approximate amount of physical memory committed for this space.
   size_t CommittedPhysicalMemory() override;
 
   // Return the available bytes without growing.
   intptr_t Available() override { return Capacity() - Size(); }
 
+  intptr_t PagesFromStart(Address addr) {
+    return static_cast<int>(addr - bottom()) / Page::kPageSize;

[Hannes Payer (out of office), 2015/05/12 17:04:17]

cast to intptr_t

[ulan, 2015/05/18 12:45:51]

Done.

+  }
+
+  size_t AllocatedSinceLastGC() {
+    intptr_t allocated = top() - to_space_.age_mark();
+    if (allocated < 0) {
+      // Runtime has lowered the top below the age mark.
+      return 0;
+    }
+    // Correctly account for non-allocatable regions at the beginning of
+    // each page from the age_mark() to the top().
+    intptr_t pages =
+        PagesFromStart(top()) - PagesFromStart(to_space_.age_mark());
+    allocated -= pages * (NewSpacePage::kObjectStartOffset);
+    DCHECK(0 <= allocated && allocated <= Size());
+    return static_cast<size_t>(allocated);
+  }
+
   // Return the maximum capacity of a semispace.
   int MaximumCapacity() {
     DCHECK(to_space_.MaximumTotalCapacity() ==
            from_space_.MaximumTotalCapacity());
     return to_space_.MaximumTotalCapacity();
   }
 
   bool IsAtMaximumCapacity() { return TotalCapacity() == MaximumCapacity(); }
 
   // Returns the initial capacity of a semispace.
@@ skipping 425 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_SPACES_H_