- Reduced the maximum capacity of a semi space from 8MB to 4MB....

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 945 matching lines @@
 #endif
 
 
 void NewSpace::Flip() {
   SemiSpace tmp = from_space_;
   from_space_ = to_space_;
   to_space_ = tmp;
 }
 
 
-bool NewSpace::Double() {
-  ASSERT(capacity_ <= maximum_capacity_ / 2);
+bool NewSpace::Grow() {
+  ASSERT(capacity_ < maximum_capacity_);
   // TODO(1240712): Failure to double the from space can result in
   // semispaces of different sizes.  In the event of that failure, the
   // to space doubling should be rolled back before returning false.
-  if (!to_space_.Double() || !from_space_.Double()) return false;
-  capacity_ *= 2;
+  if (!to_space_.Grow() || !from_space_.Grow()) return false;
+  capacity_ = to_space_.Capacity() + from_space_.Capacity();
   allocation_info_.limit = to_space_.high();
   ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
   return true;
 }
 
 
 void NewSpace::ResetAllocationInfo() {
   allocation_info_.top = to_space_.low();
   allocation_info_.limit = to_space_.high();
   ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
@@ skipping 84 matching lines @@
   return true;
 }
 
 
 void SemiSpace::TearDown() {
   start_ = NULL;
   capacity_ = 0;
 }
 
 
-bool SemiSpace::Double() {
-  if (!MemoryAllocator::CommitBlock(high(), capacity_, executable())) {
+bool SemiSpace::Grow() {
+  // Commit 50% extra space but only up to maximum capacity.
+  int extra = capacity_/2;

[Lasse Reichstein, 2009/08/13 08:45:17]

Just a thought: Would it be safer to round this up to a whole number of (OS)
pages?

+  if (capacity_ + extra > maximum_capacity_) {
+    extra = maximum_capacity_ - capacity_;
+  }
+  if (!MemoryAllocator::CommitBlock(high(), extra, executable())) {
     return false;
   }
-  capacity_ *= 2;
+  capacity_ += extra;
   return true;
 }
 
 
 #ifdef DEBUG
 void SemiSpace::Print() { }
 
 
 void SemiSpace::Verify() { }
 #endif
@@ skipping 1501 matching lines @@
                      reinterpret_cast<Object**>(object->address()
                                                 + Page::kObjectAreaSize),
                      allocation_top);
       PrintF("\n");
     }
   }
 }
 #endif  // DEBUG
 
 } }  // namespace v8::internal