hotspot/src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.cpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2002, 2010, 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
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */

 #include "precompiled.hpp"
 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
 #include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
 #include "gc_implementation/shared/mutableSpace.hpp"
 #include "memory/memRegion.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;

 void PSPromotionManager::initialize() {
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   _old_gen = heap->old_gen();
   _young_space = heap->young_gen()->to_space();

   assert(_manager_array == NULL, "Attempt to initialize twice");
   _manager_array = NEW_C_HEAP_ARRAY(PSPromotionManager*, ParallelGCThreads+1 );
   guarantee(_manager_array != NULL, "Could not initialize promotion manager");

   _stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
   guarantee(_stack_array_depth != NULL, "Cound not initialize promotion manager");

   // 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());
   }

   // 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];
 }

 PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
   assert(_manager_array != NULL, "Sanity");
   return _manager_array[ParallelGCThreads];
 }

 void PSPromotionManager::pre_scavenge() {
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   _young_space = heap->young_gen()->to_space();

   for(uint i=0; i<ParallelGCThreads+1; i++) {
     manager_array(i)->reset();
   }
 }

 void PSPromotionManager::post_scavenge() {
   TASKQUEUE_STATS_ONLY(if (PrintGCDetails && ParallelGCVerbose) print_stats());
   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
     PSPromotionManager* manager = manager_array(i);
     assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
     manager->flush_labs();
   }
 }

 #if TASKQUEUE_STATS
 void
 PSPromotionManager::print_taskqueue_stats(uint i) const {
   tty->print("%3u ", i);
   _claimed_stack_depth.stats.print();
   tty->cr();
 }

 void
 PSPromotionManager::print_local_stats(uint i) const {
   #define FMT " " SIZE_FORMAT_W(10)
   tty->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,
                 _arrays_chunked, _array_chunks_processed);
   #undef FMT
 }

 static const char* const pm_stats_hdr[] = {
   "    --------masked-------     arrays      array",
   "thr       push      steal    chunked     chunks",
   "--- ---------- ---------- ---------- ----------"
 };

 void
 PSPromotionManager::print_stats() {
   tty->print_cr("== GC Tasks Stats, GC %3d",
                 Universe::heap()->total_collections());

   tty->print("thr "); TaskQueueStats::print_header(1); tty->cr();
   tty->print("--- "); TaskQueueStats::print_header(2); tty->cr();
   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
     manager_array(i)->print_taskqueue_stats(i);
   }

   const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
   for (uint i = 0; i < hlines; ++i) tty->print_cr(pm_stats_hdr[i]);
   for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
     manager_array(i)->print_local_stats(i);
   }
 }

 void
 PSPromotionManager::reset_stats() {
   claimed_stack_depth()->stats.reset();
   _masked_pushes = _masked_steals = 0;
   _arrays_chunked = _array_chunks_processed = 0;
 }
 #endif // TASKQUEUE_STATS

 PSPromotionManager::PSPromotionManager() {
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   // We set the old lab's start array.
   _old_lab.set_start_array(old_gen()->start_array());

   uint queue_size;
   claimed_stack_depth()->initialize();
   queue_size = claimed_stack_depth()->max_elems();

   _totally_drain = (ParallelGCThreads == 1) || (GCDrainStackTargetSize == 0);
   if (_totally_drain) {
     _target_stack_size = 0;
   } else {
     // don't let the target stack size to be more than 1/4 of the entries
     _target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
                                      (uint) (queue_size / 4));
   }

   _array_chunk_size = ParGCArrayScanChunk;
   // let's choose 1.5x the chunk size
   _min_array_size_for_chunking = 3 * _array_chunk_size / 2;

   reset();
 }

 void PSPromotionManager::reset() {
   assert(stacks_empty(), "reset of non-empty stack");

   // We need to get an assert in here to make sure the labs are always flushed.

   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

   // Do not prefill the LAB's, save heap wastage!
   HeapWord* lab_base = young_space()->top();
   _young_lab.initialize(MemRegion(lab_base, (size_t)0));
   _young_gen_is_full = false;

   lab_base = old_gen()->object_space()->top();
   _old_lab.initialize(MemRegion(lab_base, (size_t)0));
   _old_gen_is_full = false;

   TASKQUEUE_STATS_ONLY(reset_stats());
 }


 void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
   totally_drain = totally_drain || _totally_drain;

 #ifdef ASSERT
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
   MutableSpace* to_space = heap->young_gen()->to_space();
   MutableSpace* old_space = heap->old_gen()->object_space();
   MutableSpace* perm_space = heap->perm_gen()->object_space();
 #endif /* ASSERT */

   OopStarTaskQueue* const tq = claimed_stack_depth();
   do {
     StarTask p;

     // Drain overflow stack first, so other threads can steal from
     // claimed stack while we work.
     while (tq->pop_overflow(p)) {
       process_popped_location_depth(p);
     }

     if (totally_drain) {
       while (tq->pop_local(p)) {
         process_popped_location_depth(p);
       }
     } else {
       while (tq->size() > _target_stack_size && tq->pop_local(p)) {
         process_popped_location_depth(p);
       }
     }
   } while (totally_drain && !tq->taskqueue_empty() || !tq->overflow_empty());

   assert(!totally_drain || tq->taskqueue_empty(), "Sanity");
   assert(totally_drain || tq->size() <= _target_stack_size, "Sanity");
   assert(tq->overflow_empty(), "Sanity");
 }

 void PSPromotionManager::flush_labs() {
   assert(stacks_empty(), "Attempt to flush lab with live stack");

   // If either promotion lab fills up, we can flush the
   // lab but not refill it, so check first.
   assert(!_young_lab.is_flushed() || _young_gen_is_full, "Sanity");
   if (!_young_lab.is_flushed())
     _young_lab.flush();

   assert(!_old_lab.is_flushed() || _old_gen_is_full, "Sanity");
   if (!_old_lab.is_flushed())
     _old_lab.flush();

   // Let PSScavenge know if we overflowed
   if (_young_gen_is_full) {
     PSScavenge::set_survivor_overflow(true);
   }
 }

 //
 // This method is pretty bulky. It would be nice to split it up
 // into smaller submethods, but we need to be careful not to hurt
 // performance.
 //

 oop PSPromotionManager::copy_to_survivor_space(oop o) {
   assert(PSScavenge::should_scavenge(&o), "Sanity");

   oop new_obj = NULL;

   // NOTE! We must be very careful with any methods that access the mark
   // in o. There may be multiple threads racing on it, and it may be forwarded
   // at any time. Do not use oop methods for accessing the mark!
   markOop test_mark = o->mark();

   // The same test as "o->is_forwarded()"
   if (!test_mark->is_marked()) {
     bool new_obj_is_tenured = false;
     size_t new_obj_size = o->size();

     // Find the objects age, MT safe.
     int age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
       test_mark->displaced_mark_helper()->age() : test_mark->age();

     // Try allocating obj in to-space (unless too old)
     if (age < PSScavenge::tenuring_threshold()) {
       new_obj = (oop) _young_lab.allocate(new_obj_size);
       if (new_obj == NULL && !_young_gen_is_full) {
         // Do we allocate directly, or flush and refill?
         if (new_obj_size > (YoungPLABSize / 2)) {
           // Allocate this object directly
           new_obj = (oop)young_space()->cas_allocate(new_obj_size);
         } else {
           // Flush and fill
           _young_lab.flush();

           HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
           if (lab_base != NULL) {
             _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
             // Try the young lab allocation again.
             new_obj = (oop) _young_lab.allocate(new_obj_size);
           } else {
             _young_gen_is_full = true;
           }
         }
       }
     }

     // Otherwise try allocating obj tenured
     if (new_obj == NULL) {
 #ifndef PRODUCT
       if (Universe::heap()->promotion_should_fail()) {
         return oop_promotion_failed(o, test_mark);
       }
 #endif  // #ifndef PRODUCT

       new_obj = (oop) _old_lab.allocate(new_obj_size);
       new_obj_is_tenured = true;

       if (new_obj == NULL) {
         if (!_old_gen_is_full) {
           // Do we allocate directly, or flush and refill?
           if (new_obj_size > (OldPLABSize / 2)) {
             // Allocate this object directly
             new_obj = (oop)old_gen()->cas_allocate(new_obj_size);
           } else {
             // Flush and fill
             _old_lab.flush();

             HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);
             if(lab_base != NULL) {
               _old_lab.initialize(MemRegion(lab_base, OldPLABSize));
               // Try the old lab allocation again.
               new_obj = (oop) _old_lab.allocate(new_obj_size);
             }
           }
         }

         // This is the promotion failed test, and code handling.
         // The code belongs here for two reasons. It is slightly
         // different thatn the code below, and cannot share the
         // CAS testing code. Keeping the code here also minimizes
         // the impact on the common case fast path code.

         if (new_obj == NULL) {
           _old_gen_is_full = true;
           return oop_promotion_failed(o, test_mark);
         }
       }
     }

     assert(new_obj != NULL, "allocation should have succeeded");

     // Copy obj
     Copy::aligned_disjoint_words((HeapWord*)o, (HeapWord*)new_obj, new_obj_size);

     // Now we have to CAS in the header.
     if (o->cas_forward_to(new_obj, test_mark)) {
       // We won any races, we "own" this object.
       assert(new_obj == o->forwardee(), "Sanity");

       // Increment age if obj still in new generation. Now that
       // we're dealing with a markOop that cannot change, it is
       // okay to use the non mt safe oop methods.
       if (!new_obj_is_tenured) {
         new_obj->incr_age();
         assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
       }

       // Do the size comparison first with new_obj_size, which we
       // already have. Hopefully, only a few objects are larger than
       // _min_array_size_for_chunking, and most of them will be arrays.
       // So, the is->objArray() test would be very infrequent.
       if (new_obj_size > _min_array_size_for_chunking &&
           new_obj->is_objArray() &&
           PSChunkLargeArrays) {
         // we'll chunk it
         oop* const masked_o = mask_chunked_array_oop(o);
         push_depth(masked_o);
         TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
       } else {
         // we'll just push its contents
         new_obj->push_contents(this);
       }
     }  else {
       // We lost, someone else "owns" this object
       guarantee(o->is_forwarded(), "Object must be forwarded if the cas failed.");

       // Try to deallocate the space.  If it was directly allocated we cannot
       // deallocate it, so we have to test.  If the deallocation fails,
       // overwrite with a filler object.
       if (new_obj_is_tenured) {
         if (!_old_lab.unallocate_object(new_obj)) {
           CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
         }
       } else if (!_young_lab.unallocate_object(new_obj)) {
         CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
       }

       // don't update this before the unallocation!
       new_obj = o->forwardee();
     }
   } else {
     assert(o->is_forwarded(), "Sanity");
     new_obj = o->forwardee();
   }

 #ifdef DEBUG
   // This code must come after the CAS test, or it will print incorrect
   // information.
   if (TraceScavenge) {
     gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (" SIZE_FORMAT ")}",
        PSScavenge::should_scavenge(&new_obj) ? "copying" : "tenuring",
        new_obj->blueprint()->internal_name(), o, new_obj, new_obj->size());
   }
 #endif

   return new_obj;
 }

 template <class T> void PSPromotionManager::process_array_chunk_work(
                                                  oop obj,
                                                  int start, int end) {
   assert(start < end, "invariant");
   T* const base      = (T*)objArrayOop(obj)->base();
   T* p               = base + start;
   T* const chunk_end = base + end;
   while (p < chunk_end) {
     if (PSScavenge::should_scavenge(p)) {
       claim_or_forward_depth(p);
     }
     ++p;
   }
 }

 void PSPromotionManager::process_array_chunk(oop old) {
   assert(PSChunkLargeArrays, "invariant");
   assert(old->is_objArray(), "invariant");
   assert(old->is_forwarded(), "invariant");

   TASKQUEUE_STATS_ONLY(++_array_chunks_processed);

   oop const obj = old->forwardee();

   int start;
   int const end = arrayOop(old)->length();
   if (end > (int) _min_array_size_for_chunking) {
     // we'll chunk more
     start = end - _array_chunk_size;
     assert(start > 0, "invariant");
     arrayOop(old)->set_length(start);
     push_depth(mask_chunked_array_oop(old));
     TASKQUEUE_STATS_ONLY(++_masked_pushes);
   } else {
     // this is the final chunk for this array
     start = 0;
     int const actual_length = arrayOop(obj)->length();
     arrayOop(old)->set_length(actual_length);
   }

   if (UseCompressedOops) {
     process_array_chunk_work<narrowOop>(obj, start, end);
   } else {
     process_array_chunk_work<oop>(obj, start, end);
   }
 }

 oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {
   assert(_old_gen_is_full || PromotionFailureALot, "Sanity");

   // Attempt to CAS in the header.
   // This tests if the header is still the same as when
   // this started.  If it is the same (i.e., no forwarding
   // pointer has been installed), then this thread owns
   // it.
   if (obj->cas_forward_to(obj, obj_mark)) {
     // We won any races, we "own" this object.
     assert(obj == obj->forwardee(), "Sanity");

     obj->push_contents(this);

     // Save the mark if needed
     PSScavenge::oop_promotion_failed(obj, obj_mark);
   }  else {
     // We lost, someone else "owns" this object
     guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");

     // No unallocation to worry about.
     obj = obj->forwardee();
   }

 #ifdef DEBUG
   if (TraceScavenge) {
     gclog_or_tty->print_cr("{%s %s 0x%x (%d)}",
                            "promotion-failure",
                            obj->blueprint()->internal_name(),
                            obj, obj->size());

   }
 #endif

   return obj;
 }
	/*
	* Copyright (c) 2002, 2010, 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
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*
	*/

	#include "precompiled.hpp"
	#include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp"
	#include "gc_implementation/parallelScavenge/psOldGen.hpp"
	#include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
	#include "gc_implementation/parallelScavenge/psScavenge.inline.hpp"
	#include "gc_implementation/shared/mutableSpace.hpp"
	#include "memory/memRegion.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;

	void PSPromotionManager::initialize() {
	ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
	assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

	_old_gen = heap->old_gen();
	_young_space = heap->young_gen()->to_space();

	assert(_manager_array == NULL, "Attempt to initialize twice");
	_manager_array = NEW_C_HEAP_ARRAY(PSPromotionManager*, ParallelGCThreads+1 );
	guarantee(_manager_array != NULL, "Could not initialize promotion manager");

	_stack_array_depth = new OopStarTaskQueueSet(ParallelGCThreads);
	guarantee(_stack_array_depth != NULL, "Cound not initialize promotion manager");

	// 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());
	}

	// 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];
	}

	PSPromotionManager* PSPromotionManager::vm_thread_promotion_manager() {
	assert(_manager_array != NULL, "Sanity");
	return _manager_array[ParallelGCThreads];
	}

	void PSPromotionManager::pre_scavenge() {
	ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
	assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

	_young_space = heap->young_gen()->to_space();

	for(uint i=0; i<ParallelGCThreads+1; i++) {
	manager_array(i)->reset();
	}
	}

	void PSPromotionManager::post_scavenge() {
	TASKQUEUE_STATS_ONLY(if (PrintGCDetails && ParallelGCVerbose) print_stats());
	for (uint i = 0; i < ParallelGCThreads + 1; i++) {
	PSPromotionManager* manager = manager_array(i);
	assert(manager->claimed_stack_depth()->is_empty(), "should be empty");
	manager->flush_labs();
	}
	}

	#if TASKQUEUE_STATS
	void
	PSPromotionManager::print_taskqueue_stats(uint i) const {
	tty->print("%3u ", i);
	_claimed_stack_depth.stats.print();
	tty->cr();
	}

	void
	PSPromotionManager::print_local_stats(uint i) const {
	#define FMT " " SIZE_FORMAT_W(10)
	tty->print_cr("%3u" FMT FMT FMT FMT, i, _masked_pushes, _masked_steals,
	_arrays_chunked, _array_chunks_processed);
	#undef FMT
	}

	static const char* const pm_stats_hdr[] = {
	" --------masked------- arrays array",
	"thr push steal chunked chunks",
	"--- ---------- ---------- ---------- ----------"
	};

	void
	PSPromotionManager::print_stats() {
	tty->print_cr("== GC Tasks Stats, GC %3d",
	Universe::heap()->total_collections());

	tty->print("thr "); TaskQueueStats::print_header(1); tty->cr();
	tty->print("--- "); TaskQueueStats::print_header(2); tty->cr();
	for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
	manager_array(i)->print_taskqueue_stats(i);
	}

	const uint hlines = sizeof(pm_stats_hdr) / sizeof(pm_stats_hdr[0]);
	for (uint i = 0; i < hlines; ++i) tty->print_cr(pm_stats_hdr[i]);
	for (uint i = 0; i < ParallelGCThreads + 1; ++i) {
	manager_array(i)->print_local_stats(i);
	}
	}

	void
	PSPromotionManager::reset_stats() {
	claimed_stack_depth()->stats.reset();
	_masked_pushes = _masked_steals = 0;
	_arrays_chunked = _array_chunks_processed = 0;
	}
	#endif // TASKQUEUE_STATS

	PSPromotionManager::PSPromotionManager() {
	ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
	assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

	// We set the old lab's start array.
	_old_lab.set_start_array(old_gen()->start_array());

	uint queue_size;
	claimed_stack_depth()->initialize();
	queue_size = claimed_stack_depth()->max_elems();

	_totally_drain = (ParallelGCThreads == 1) \|\| (GCDrainStackTargetSize == 0);
	if (_totally_drain) {
	_target_stack_size = 0;
	} else {
	// don't let the target stack size to be more than 1/4 of the entries
	_target_stack_size = (uint) MIN2((uint) GCDrainStackTargetSize,
	(uint) (queue_size / 4));
	}

	_array_chunk_size = ParGCArrayScanChunk;
	// let's choose 1.5x the chunk size
	_min_array_size_for_chunking = 3 * _array_chunk_size / 2;

	reset();
	}

	void PSPromotionManager::reset() {
	assert(stacks_empty(), "reset of non-empty stack");

	// We need to get an assert in here to make sure the labs are always flushed.

	ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
	assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");

	// Do not prefill the LAB's, save heap wastage!
	HeapWord* lab_base = young_space()->top();
	_young_lab.initialize(MemRegion(lab_base, (size_t)0));
	_young_gen_is_full = false;

	lab_base = old_gen()->object_space()->top();
	_old_lab.initialize(MemRegion(lab_base, (size_t)0));
	_old_gen_is_full = false;

	TASKQUEUE_STATS_ONLY(reset_stats());
	}


	void PSPromotionManager::drain_stacks_depth(bool totally_drain) {
	totally_drain = totally_drain \|\| _totally_drain;

	#ifdef ASSERT
	ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
	assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
	MutableSpace* to_space = heap->young_gen()->to_space();
	MutableSpace* old_space = heap->old_gen()->object_space();
	MutableSpace* perm_space = heap->perm_gen()->object_space();
	#endif /* ASSERT */

	OopStarTaskQueue* const tq = claimed_stack_depth();
	do {
	StarTask p;

	// Drain overflow stack first, so other threads can steal from
	// claimed stack while we work.
	while (tq->pop_overflow(p)) {
	process_popped_location_depth(p);
	}

	if (totally_drain) {
	while (tq->pop_local(p)) {
	process_popped_location_depth(p);
	}
	} else {
	while (tq->size() > _target_stack_size && tq->pop_local(p)) {
	process_popped_location_depth(p);
	}
	}
	} while (totally_drain && !tq->taskqueue_empty() \|\| !tq->overflow_empty());

	assert(!totally_drain \|\| tq->taskqueue_empty(), "Sanity");
	assert(totally_drain \|\| tq->size() <= _target_stack_size, "Sanity");
	assert(tq->overflow_empty(), "Sanity");
	}

	void PSPromotionManager::flush_labs() {
	assert(stacks_empty(), "Attempt to flush lab with live stack");

	// If either promotion lab fills up, we can flush the
	// lab but not refill it, so check first.
	assert(!_young_lab.is_flushed() \|\| _young_gen_is_full, "Sanity");
	if (!_young_lab.is_flushed())
	_young_lab.flush();

	assert(!_old_lab.is_flushed() \|\| _old_gen_is_full, "Sanity");
	if (!_old_lab.is_flushed())
	_old_lab.flush();

	// Let PSScavenge know if we overflowed
	if (_young_gen_is_full) {
	PSScavenge::set_survivor_overflow(true);
	}
	}

	//
	// This method is pretty bulky. It would be nice to split it up
	// into smaller submethods, but we need to be careful not to hurt
	// performance.
	//

	oop PSPromotionManager::copy_to_survivor_space(oop o) {
	assert(PSScavenge::should_scavenge(&o), "Sanity");

	oop new_obj = NULL;

	// NOTE! We must be very careful with any methods that access the mark
	// in o. There may be multiple threads racing on it, and it may be forwarded
	// at any time. Do not use oop methods for accessing the mark!
	markOop test_mark = o->mark();

	// The same test as "o->is_forwarded()"
	if (!test_mark->is_marked()) {
	bool new_obj_is_tenured = false;
	size_t new_obj_size = o->size();

	// Find the objects age, MT safe.
	int age = (test_mark->has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
	test_mark->displaced_mark_helper()->age() : test_mark->age();

	// Try allocating obj in to-space (unless too old)
	if (age < PSScavenge::tenuring_threshold()) {
	new_obj = (oop) _young_lab.allocate(new_obj_size);
	if (new_obj == NULL && !_young_gen_is_full) {
	// Do we allocate directly, or flush and refill?
	if (new_obj_size > (YoungPLABSize / 2)) {
	// Allocate this object directly
	new_obj = (oop)young_space()->cas_allocate(new_obj_size);
	} else {
	// Flush and fill
	_young_lab.flush();

	HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
	if (lab_base != NULL) {
	_young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
	// Try the young lab allocation again.
	new_obj = (oop) _young_lab.allocate(new_obj_size);
	} else {
	_young_gen_is_full = true;
	}
	}
	}
	}

	// Otherwise try allocating obj tenured
	if (new_obj == NULL) {
	#ifndef PRODUCT
	if (Universe::heap()->promotion_should_fail()) {
	return oop_promotion_failed(o, test_mark);
	}
	#endif // #ifndef PRODUCT

	new_obj = (oop) _old_lab.allocate(new_obj_size);
	new_obj_is_tenured = true;

	if (new_obj == NULL) {
	if (!_old_gen_is_full) {
	// Do we allocate directly, or flush and refill?
	if (new_obj_size > (OldPLABSize / 2)) {
	// Allocate this object directly
	new_obj = (oop)old_gen()->cas_allocate(new_obj_size);
	} else {
	// Flush and fill
	_old_lab.flush();

	HeapWord* lab_base = old_gen()->cas_allocate(OldPLABSize);
	if(lab_base != NULL) {
	_old_lab.initialize(MemRegion(lab_base, OldPLABSize));
	// Try the old lab allocation again.
	new_obj = (oop) _old_lab.allocate(new_obj_size);
	}
	}
	}

	// This is the promotion failed test, and code handling.
	// The code belongs here for two reasons. It is slightly
	// different thatn the code below, and cannot share the
	// CAS testing code. Keeping the code here also minimizes
	// the impact on the common case fast path code.

	if (new_obj == NULL) {
	_old_gen_is_full = true;
	return oop_promotion_failed(o, test_mark);
	}
	}
	}

	assert(new_obj != NULL, "allocation should have succeeded");

	// Copy obj
	Copy::aligned_disjoint_words((HeapWord)o, (HeapWord)new_obj, new_obj_size);

	// Now we have to CAS in the header.
	if (o->cas_forward_to(new_obj, test_mark)) {
	// We won any races, we "own" this object.
	assert(new_obj == o->forwardee(), "Sanity");

	// Increment age if obj still in new generation. Now that
	// we're dealing with a markOop that cannot change, it is
	// okay to use the non mt safe oop methods.
	if (!new_obj_is_tenured) {
	new_obj->incr_age();
	assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
	}

	// Do the size comparison first with new_obj_size, which we
	// already have. Hopefully, only a few objects are larger than
	// _min_array_size_for_chunking, and most of them will be arrays.
	// So, the is->objArray() test would be very infrequent.
	if (new_obj_size > _min_array_size_for_chunking &&
	new_obj->is_objArray() &&
	PSChunkLargeArrays) {
	// we'll chunk it
	oop* const masked_o = mask_chunked_array_oop(o);
	push_depth(masked_o);
	TASKQUEUE_STATS_ONLY(++_arrays_chunked; ++_masked_pushes);
	} else {
	// we'll just push its contents
	new_obj->push_contents(this);
	}
	} else {
	// We lost, someone else "owns" this object
	guarantee(o->is_forwarded(), "Object must be forwarded if the cas failed.");

	// Try to deallocate the space. If it was directly allocated we cannot
	// deallocate it, so we have to test. If the deallocation fails,
	// overwrite with a filler object.
	if (new_obj_is_tenured) {
	if (!_old_lab.unallocate_object(new_obj)) {
	CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
	}
	} else if (!_young_lab.unallocate_object(new_obj)) {
	CollectedHeap::fill_with_object((HeapWord*) new_obj, new_obj_size);
	}

	// don't update this before the unallocation!
	new_obj = o->forwardee();
	}
	} else {
	assert(o->is_forwarded(), "Sanity");
	new_obj = o->forwardee();
	}

	#ifdef DEBUG
	// This code must come after the CAS test, or it will print incorrect
	// information.
	if (TraceScavenge) {
	gclog_or_tty->print_cr("{%s %s " PTR_FORMAT " -> " PTR_FORMAT " (" SIZE_FORMAT ")}",
	PSScavenge::should_scavenge(&new_obj) ? "copying" : "tenuring",
	new_obj->blueprint()->internal_name(), o, new_obj, new_obj->size());
	}
	#endif

	return new_obj;
	}

	template <class T> void PSPromotionManager::process_array_chunk_work(
	oop obj,
	int start, int end) {
	assert(start < end, "invariant");
	T* const base = (T*)objArrayOop(obj)->base();
	T* p = base + start;
	T* const chunk_end = base + end;
	while (p < chunk_end) {
	if (PSScavenge::should_scavenge(p)) {
	claim_or_forward_depth(p);
	}
	++p;
	}
	}

	void PSPromotionManager::process_array_chunk(oop old) {
	assert(PSChunkLargeArrays, "invariant");
	assert(old->is_objArray(), "invariant");
	assert(old->is_forwarded(), "invariant");

	TASKQUEUE_STATS_ONLY(++_array_chunks_processed);

	oop const obj = old->forwardee();

	int start;
	int const end = arrayOop(old)->length();
	if (end > (int) _min_array_size_for_chunking) {
	// we'll chunk more
	start = end - _array_chunk_size;
	assert(start > 0, "invariant");
	arrayOop(old)->set_length(start);
	push_depth(mask_chunked_array_oop(old));
	TASKQUEUE_STATS_ONLY(++_masked_pushes);
	} else {
	// this is the final chunk for this array
	start = 0;
	int const actual_length = arrayOop(obj)->length();
	arrayOop(old)->set_length(actual_length);
	}

	if (UseCompressedOops) {
	process_array_chunk_work<narrowOop>(obj, start, end);
	} else {
	process_array_chunk_work<oop>(obj, start, end);
	}
	}

	oop PSPromotionManager::oop_promotion_failed(oop obj, markOop obj_mark) {
	assert(_old_gen_is_full \|\| PromotionFailureALot, "Sanity");

	// Attempt to CAS in the header.
	// This tests if the header is still the same as when
	// this started. If it is the same (i.e., no forwarding
	// pointer has been installed), then this thread owns
	// it.
	if (obj->cas_forward_to(obj, obj_mark)) {
	// We won any races, we "own" this object.
	assert(obj == obj->forwardee(), "Sanity");

	obj->push_contents(this);

	// Save the mark if needed
	PSScavenge::oop_promotion_failed(obj, obj_mark);
	} else {
	// We lost, someone else "owns" this object
	guarantee(obj->is_forwarded(), "Object must be forwarded if the cas failed.");

	// No unallocation to worry about.
	obj = obj->forwardee();
	}

	#ifdef DEBUG
	if (TraceScavenge) {
	gclog_or_tty->print_cr("{%s %s 0x%x (%d)}",
	"promotion-failure",
	obj->blueprint()->internal_name(),
	obj, obj->size());

	}
	#endif

	return obj;
	}