Parallel and concurrent sweeping.

src/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // met:
 //
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@@ skipping 1255 matching lines @@
 
   // Used for updating survived_since_last_expansion_ at function end.
   intptr_t survived_watermark = PromotedSpaceSizeOfObjects();
 
   CheckNewSpaceExpansionCriteria();
 
   SelectScavengingVisitorsTable();
 
   incremental_marking()->PrepareForScavenge();
 
-  AdvanceSweepers(static_cast<int>(new_space_.Size()));
+  MarkCompactCollector* mark_compact = mark_compact_collector();
+
+  if (!mark_compact->AreSweeperThreadsActivated()) {
+     AdvanceSweepers(static_cast<int>(new_space_.Size()));
+  } else if (FLAG_concurrent_sweeping) {
+    mark_compact->StealMemoryFromSweeperThreads(paged_space(OLD_DATA_SPACE));
+    mark_compact->StealMemoryFromSweeperThreads(paged_space(OLD_POINTER_SPACE));
+  }

[Michael Starzinger, 2013/01/28 16:30:18]

What we actually wanna ensure here is that we made enough progress in sweeping
so that the Scavanger can in the worst case promote all objects from new-space.
So I think the right thing here is to call PagedSpace::EnsureSweeperProgress on
the old-data-space and old-pointer-space, no matter which mode we are in.

[Hannes Payer (out of office), 2013/01/30 10:11:27]

Right, but this changes the current non-parallel non-concurrent behavior.

On 2013/01/28 16:30:18, Michael Starzinger wrote:

 
   // Flip the semispaces.  After flipping, to space is empty, from space has
   // live objects.
   new_space_.Flip();
   new_space_.ResetAllocationInfo();
 
   // We need to sweep newly copied objects which can be either in the
   // to space or promoted to the old generation.  For to-space
   // objects, we treat the bottom of the to space as a queue.  Newly
   // copied and unswept objects lie between a 'front' mark and the
@@ skipping 4078 matching lines @@
 
   // By doing small chunks of GC work in each IdleNotification,
   // perform a round of incremental GCs and after that wait until
   // the mutator creates enough garbage to justify a new round.
   // An incremental GC progresses as follows:
   // 1. many incremental marking steps,
   // 2. one old space mark-sweep-compact,
   // 3. many lazy sweep steps.
   // Use mark-sweep-compact events to count incremental GCs in a round.
 
 

[Michael Starzinger, 2013/01/28 16:30:18]

I know it's not your change, but drop one of the two empty newlines.

[Hannes Payer (out of office), 2013/01/30 10:11:27]

Done.

   if (incremental_marking()->IsStopped()) {
-    if (!IsSweepingComplete() &&
+    if (!mark_compact_collector()->AreSweeperThreadsActivated() &&
+        !IsSweepingComplete() &&
         !AdvanceSweepers(static_cast<int>(step_size))) {
       return false;
     }
   }
 
   if (mark_sweeps_since_idle_round_started_ >= kMaxMarkSweepsInIdleRound) {
     if (EnoughGarbageSinceLastIdleRound()) {
       StartIdleRound();
     } else {
       return true;
@@ skipping 1968 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   memcpy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   memcpy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal