8022880: False sharing between PSPromotionManager instances

Pad the PSPromotionManager instances in the manager array.

Reviewed-by: brutisso, jmasa

hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp

@@ -50,6 +50,7 @@
 #include "memory/genMarkSweep.hpp"
 #include "memory/genOopClosures.inline.hpp"
 #include "memory/iterator.hpp"
+#include "memory/padded.hpp"
 #include "memory/referencePolicy.hpp"
 #include "memory/resourceArea.hpp"
 #include "memory/tenuredGeneration.hpp"

hotspot/src/share/vm/gc_implementation/parNew/parNewGeneration.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -29,6 +29,7 @@
 #include "gc_implementation/shared/parGCAllocBuffer.hpp"
 #include "gc_implementation/shared/copyFailedInfo.hpp"
 #include "memory/defNewGeneration.hpp"
+#include "memory/padded.hpp"
 #include "utilities/taskqueue.hpp"
 
 class ChunkArray;

hotspot/src/share/vm/gc_implementation/parNew/parOopClosures.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2012, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,7 @@
 #define SHARE_VM_GC_IMPLEMENTATION_PARNEW_PAROOPCLOSURES_HPP
 
 #include "memory/genOopClosures.hpp"
+#include "memory/padded.hpp"
 
 // Closures for ParNewGeneration
 

hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.cpp

@@ -29,14 +29,16 @@
 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
 #include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/mutableSpace.hpp"
+#include "memory/allocation.inline.hpp"
 #include "memory/memRegion.hpp"
+#include "memory/padded.inline.hpp"
 #include "oops/oop.inline.hpp"
 #include "oops/oop.psgc.inline.hpp"
 
-PSPromotionManager**         PSPromotionManager::_manager_array = NULL;
-OopStarTaskQueueSet*         PSPromotionManager::_stack_array_depth = NULL;
-PSOldGen*                    PSPromotionManager::_old_gen = NULL;
-MutableSpace*                PSPromotionManager::_young_space = NULL;
+PaddedEnd<PSPromotionManager>* PSPromotionManager::_manager_array = NULL;
+OopStarTaskQueueSet*           PSPromotionManager::_stack_array_depth = NULL;
+PSOldGen*                      PSPromotionManager::_old_gen = NULL;
+MutableSpace*                  PSPromotionManager::_young_space = NULL;
 
 void PSPromotionManager::initialize() {
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
@@ -45,8 +47,10 @@ void PSPromotionManager::initialize() {
   _old_gen = heap->old_gen();
   _young_space = heap->young_gen()->to_space();
 
+  // To prevent false sharing, we pad the PSPromotionManagers
+  // and make sure that the first instance starts at a cache line.
   assert(_manager_array == NULL, "Attempt to initialize twice");
-  _manager_array = NEW_C_HEAP_ARRAY(PSPromotionManager*, ParallelGCThreads+1, mtGC);
+  _manager_array = PaddedArray<PSPromotionManager, mtGC>::create_unfreeable(ParallelGCThreads + 1);
   guarantee(_manager_array != NULL, "Could not initialize promotion manager");
 
   _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
@@ -54,26 +58,21 @@ void PSPromotionManager::initialize() {
 
   // Create and register the PSPromotionManager(s) for the worker threads.
   for(uint i=0; i<ParallelGCThreads; i++) {
-    _manager_array[i] = new PSPromotionManager();
-    guarantee(_manager_array[i] != NULL, "Could not create PSPromotionManager");
-    stack_array_depth()->register_queue(i, _manager_array[i]->claimed_stack_depth());
+    stack_array_depth()->register_queue(i, _manager_array[i].claimed_stack_depth());
   }
-
   // The VMThread gets its own PSPromotionManager, which is not available
   // for work stealing.
-  _manager_array[ParallelGCThreads] = new PSPromotionManager();
-  guarantee(_manager_array[ParallelGCThreads] != NULL, "Could not create PSPromotionManager");
 }
 
 PSPromotionManager* PSPromotionManager::gc_thread_promotion_manager(int index) {
   assert(index >= 0 && index < (int)ParallelGCThreads, "index out of range");
   assert(_manager_array != NULL, "Sanity");
-  return _manager_array[index];
+  return &_manager_array[index];
 }
 
 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
   assert(_manager_array != NULL, "Sanity");
-  return _manager_array[ParallelGCThreads];
+  return &_manager_array[ParallelGCThreads];
 }
 
 void PSPromotionManager::pre_scavenge() {

hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.hpp

@@ -29,6 +29,8 @@
 #include "gc_implementation/shared/gcTrace.hpp"
 #include "gc_implementation/shared/copyFailedInfo.hpp"
 #include "memory/allocation.hpp"
+#include "memory/padded.hpp"
+#include "utilities/globalDefinitions.hpp"
 #include "utilities/taskqueue.hpp"
 
 //
@@ -51,14 +53,14 @@ class MutableSpace;
 class PSOldGen;
 class ParCompactionManager;
 
-class PSPromotionManager : public CHeapObj<mtGC> {
+class PSPromotionManager VALUE_OBJ_CLASS_SPEC {
   friend class PSScavenge;
   friend class PSRefProcTaskExecutor;
  private:
-  static PSPromotionManager**         _manager_array;
-  static OopStarTaskQueueSet*         _stack_array_depth;
-  static PSOldGen*                    _old_gen;
-  static MutableSpace*                _young_space;
+  static PaddedEnd<PSPromotionManager>* _manager_array;
+  static OopStarTaskQueueSet*           _stack_array_depth;
+  static PSOldGen*                      _old_gen;
+  static MutableSpace*                  _young_space;
 
 #if TASKQUEUE_STATS
   size_t                              _masked_pushes;

hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.inline.hpp

@@ -32,7 +32,7 @@
 inline PSPromotionManager* PSPromotionManager::manager_array(int index) {
   assert(_manager_array != NULL, "access of NULL manager_array");
   assert(index >= 0 && index <= (int)ParallelGCThreads, "out of range manager_array access");
-  return _manager_array[index];
+  return &_manager_array[index];
 }
 
 template <class T>