Grow old generation slower on low-memory devices.

src/heap.cc

 // Copyright 2012 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 63 matching lines @@
       reserved_semispace_size_(8 * (kPointerSize / 4) * MB),
       max_semispace_size_(8 * (kPointerSize / 4)  * MB),
       initial_semispace_size_(Page::kPageSize),
       max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
       max_executable_size_(256ul * (kPointerSize / 4) * MB),
 // Variables set based on semispace_size_ and old_generation_size_ in
 // ConfigureHeap (survived_since_last_expansion_, external_allocation_limit_)
 // Will be 4 * reserved_semispace_size_ to ensure that young
 // generation can be aligned to its size.
       maximum_committed_(0),
+      old_generation_growing_factor_(4),
       survived_since_last_expansion_(0),
       sweep_generation_(0),
       always_allocate_scope_depth_(0),
       linear_allocation_scope_depth_(0),
       contexts_disposed_(0),
       global_ic_age_(0),
       flush_monomorphic_ics_(false),
       scan_on_scavenge_pages_(0),
       new_space_(this),
       old_pointer_space_(NULL),
@@ skipping 5851 matching lines @@
                                          Page::kPageSize));
 
   // We rely on being able to allocate new arrays in paged spaces.
   ASSERT(Page::kMaxRegularHeapObjectSize >=
          (JSArray::kSize +
           FixedArray::SizeFor(JSObject::kInitialMaxFastElementArray) +
           AllocationMemento::kSize));
 
   code_range_size_ = code_range_size;
 
+  // We set the old generation growing factor to 2 to grow the heap slower on
+  // low memory devices.
+  if (max_old_generation_size_ <= 256 * MB) {

[Michael Starzinger, 2014/04/15 12:11:50]

I personally am fine with hard-coding this constant. But I am not sure how much
this duplicates "magic constants" between embedders and V8. I am deferring to
Ross' opinion about this.

[rmcilroy, 2014/04/15 12:43:01]

I'm fine with this being hard-coded as well, but could we extract a constant
somewhere for the 256MB and use it both here and in
ResourceConstraints::ConfigureDefaultS? That way, if we decide to change the
heap size of a low-mem device it will change both places. 

[Hannes Payer (out of office), 2014/04/16 07:53:01]

Done.

[Hannes Payer (out of office), 2014/04/16 07:53:01]

Done.

+    old_generation_growing_factor_ = 2;
+  }
+
   configured_ = true;
   return true;
 }
 
 
 bool Heap::ConfigureHeapDefault() {
   return ConfigureHeap(static_cast<intptr_t>(FLAG_max_new_space_size / 2) * KB,
                        static_cast<intptr_t>(FLAG_max_old_space_size) * MB,
                        static_cast<intptr_t>(FLAG_max_executable_size) * MB,
                        static_cast<intptr_t>(0));
@@ skipping 1391 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   OS::MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   OS::MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal