src/hotspot/share/gc/g1/g1AllocRegion.cpp - platform/libcore - Git at Google

 /*
  * Copyright (c) 2011, 2018, 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/g1/g1AllocRegion.inline.hpp"
 #include "gc/g1/g1EvacStats.inline.hpp"
 #include "gc/g1/g1CollectedHeap.inline.hpp"
 #include "logging/log.hpp"
 #include "logging/logStream.hpp"
 #include "memory/resourceArea.hpp"
 #include "runtime/orderAccess.hpp"
 #include "utilities/align.hpp"

 G1CollectedHeap* G1AllocRegion::_g1h = NULL;
 HeapRegion* G1AllocRegion::_dummy_region = NULL;

 void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
   assert(_dummy_region == NULL, "should be set once");
   assert(dummy_region != NULL, "pre-condition");
   assert(dummy_region->free() == 0, "pre-condition");

   // Make sure that any allocation attempt on this region will fail
   // and will not trigger any asserts.
   assert(dummy_region->allocate_no_bot_updates(1) == NULL, "should fail");
   assert(dummy_region->allocate(1) == NULL, "should fail");
   DEBUG_ONLY(size_t assert_tmp);
   assert(dummy_region->par_allocate_no_bot_updates(1, 1, &assert_tmp) == NULL, "should fail");
   assert(dummy_region->par_allocate(1, 1, &assert_tmp) == NULL, "should fail");

   _g1h = g1h;
   _dummy_region = dummy_region;
 }

 size_t G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region) {
   assert(alloc_region != NULL && alloc_region != _dummy_region,
          "pre-condition");
   size_t result = 0;

   // Other threads might still be trying to allocate using a CAS out
   // of the region we are trying to retire, as they can do so without
   // holding the lock. So, we first have to make sure that noone else
   // can allocate out of it by doing a maximal allocation. Even if our
   // CAS attempt fails a few times, we'll succeed sooner or later
   // given that failed CAS attempts mean that the region is getting
   // closed to being full.
   size_t free_word_size = alloc_region->free() / HeapWordSize;

   // This is the minimum free chunk we can turn into a dummy
   // object. If the free space falls below this, then noone can
   // allocate in this region anyway (all allocation requests will be
   // of a size larger than this) so we won't have to perform the dummy
   // allocation.
   size_t min_word_size_to_fill = CollectedHeap::min_fill_size();

   while (free_word_size >= min_word_size_to_fill) {
     HeapWord* dummy = par_allocate(alloc_region, free_word_size);
     if (dummy != NULL) {
       // If the allocation was successful we should fill in the space.
       CollectedHeap::fill_with_object(dummy, free_word_size);
       alloc_region->set_pre_dummy_top(dummy);
       result += free_word_size * HeapWordSize;
       break;
     }

     free_word_size = alloc_region->free() / HeapWordSize;
     // It's also possible that someone else beats us to the
     // allocation and they fill up the region. In that case, we can
     // just get out of the loop.
   }
   result += alloc_region->free();

   assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
          "post-condition");
   return result;
 }

 size_t G1AllocRegion::retire_internal(HeapRegion* alloc_region, bool fill_up) {
   // We never have to check whether the active region is empty or not,
   // and potentially free it if it is, given that it's guaranteed that
   // it will never be empty.
   size_t waste = 0;
   assert_alloc_region(!alloc_region->is_empty(),
       "the alloc region should never be empty");

   if (fill_up) {
     waste = fill_up_remaining_space(alloc_region);
   }

   assert_alloc_region(alloc_region->used() >= _used_bytes_before, "invariant");
   size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
   retire_region(alloc_region, allocated_bytes);
   _used_bytes_before = 0;

   return waste;
 }

 size_t G1AllocRegion::retire(bool fill_up) {
   assert_alloc_region(_alloc_region != NULL, "not initialized properly");

   size_t waste = 0;

   trace("retiring");
   HeapRegion* alloc_region = _alloc_region;
   if (alloc_region != _dummy_region) {
     waste = retire_internal(alloc_region, fill_up);
     reset_alloc_region();
   }
   trace("retired");

   return waste;
 }

 HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
                                                        bool force) {
   assert_alloc_region(_alloc_region == _dummy_region, "pre-condition");
   assert_alloc_region(_used_bytes_before == 0, "pre-condition");

   trace("attempting region allocation");
   HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
   if (new_alloc_region != NULL) {
     new_alloc_region->reset_pre_dummy_top();
     // Need to do this before the allocation
     _used_bytes_before = new_alloc_region->used();
     HeapWord* result = allocate(new_alloc_region, word_size);
     assert_alloc_region(result != NULL, "the allocation should succeeded");

     OrderAccess::storestore();
     // Note that we first perform the allocation and then we store the
     // region in _alloc_region. This is the reason why an active region
     // can never be empty.
     update_alloc_region(new_alloc_region);
     trace("region allocation successful");
     return result;
   } else {
     trace("region allocation failed");
     return NULL;
   }
   ShouldNotReachHere();
 }

 void G1AllocRegion::init() {
   trace("initializing");
   assert_alloc_region(_alloc_region == NULL && _used_bytes_before == 0, "pre-condition");
   assert_alloc_region(_dummy_region != NULL, "should have been set");
   _alloc_region = _dummy_region;
   _count = 0;
   trace("initialized");
 }

 void G1AllocRegion::set(HeapRegion* alloc_region) {
   trace("setting");
   // We explicitly check that the region is not empty to make sure we
   // maintain the "the alloc region cannot be empty" invariant.
   assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");
   assert_alloc_region(_alloc_region == _dummy_region &&
                          _used_bytes_before == 0 && _count == 0,
                          "pre-condition");

   _used_bytes_before = alloc_region->used();
   _alloc_region = alloc_region;
   _count += 1;
   trace("set");
 }

 void G1AllocRegion::update_alloc_region(HeapRegion* alloc_region) {
   trace("update");
   // We explicitly check that the region is not empty to make sure we
   // maintain the "the alloc region cannot be empty" invariant.
   assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");

   _alloc_region = alloc_region;
   _count += 1;
   trace("updated");
 }

 HeapRegion* G1AllocRegion::release() {
   trace("releasing");
   HeapRegion* alloc_region = _alloc_region;
   retire(false /* fill_up */);
   assert_alloc_region(_alloc_region == _dummy_region, "post-condition of retire()");
   _alloc_region = NULL;
   trace("released");
   return (alloc_region == _dummy_region) ? NULL : alloc_region;
 }

 #ifndef PRODUCT
 void G1AllocRegion::trace(const char* str, size_t min_word_size, size_t desired_word_size, size_t actual_word_size, HeapWord* result) {
   // All the calls to trace that set either just the size or the size
   // and the result are considered part of detailed tracing and are
   // skipped during other tracing.

   Log(gc, alloc, region) log;

   if (!log.is_debug()) {
     return;
   }

   bool detailed_info = log.is_trace();

   if ((actual_word_size == 0 && result == NULL) || detailed_info) {
     ResourceMark rm;
     LogStream ls_trace(log.trace());
     LogStream ls_debug(log.debug());
     outputStream* out = detailed_info ? &ls_trace : &ls_debug;

     out->print("%s: %u ", _name, _count);

     if (_alloc_region == NULL) {
       out->print("NULL");
     } else if (_alloc_region == _dummy_region) {
       out->print("DUMMY");
     } else {
       out->print(HR_FORMAT, HR_FORMAT_PARAMS(_alloc_region));
     }

     out->print(" : %s", str);

     if (detailed_info) {
       if (result != NULL) {
         out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT " actual " SIZE_FORMAT " " PTR_FORMAT,
                      min_word_size, desired_word_size, actual_word_size, p2i(result));
       } else if (min_word_size != 0) {
         out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT, min_word_size, desired_word_size);
       }
     }
     out->cr();
   }
 }
 #endif // PRODUCT

 G1AllocRegion::G1AllocRegion(const char* name,
                              bool bot_updates)
   : _name(name), _bot_updates(bot_updates),
     _alloc_region(NULL), _count(0),
     _used_bytes_before(0) { }


 HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
                                                     bool force) {
   return _g1h->new_mutator_alloc_region(word_size, force);
 }

 void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
                                        size_t allocated_bytes) {
   _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
 }

 void MutatorAllocRegion::init() {
   assert(_retained_alloc_region == NULL, "Pre-condition");
   G1AllocRegion::init();
   _wasted_bytes = 0;
 }

 bool MutatorAllocRegion::should_retain(HeapRegion* region) {
   size_t free_bytes = region->free();
   if (free_bytes < MinTLABSize) {
     return false;
   }

   if (_retained_alloc_region != NULL &&
       free_bytes < _retained_alloc_region->free()) {
     return false;
   }

   return true;
 }

 size_t MutatorAllocRegion::retire(bool fill_up) {
   size_t waste = 0;
   trace("retiring");
   HeapRegion* current_region = get();
   if (current_region != NULL) {
     // Retain the current region if it fits a TLAB and has more
     // free than the currently retained region.
     if (should_retain(current_region)) {
       trace("mutator retained");
       if (_retained_alloc_region != NULL) {
         waste = retire_internal(_retained_alloc_region, true);
       }
       _retained_alloc_region = current_region;
     } else {
       waste = retire_internal(current_region, fill_up);
     }
     reset_alloc_region();
   }

   _wasted_bytes += waste;
   trace("retired");
   return waste;
 }

 size_t MutatorAllocRegion::used_in_alloc_regions() {
   size_t used = 0;
   HeapRegion* hr = get();
   if (hr != NULL) {
     used += hr->used();
   }

   hr = _retained_alloc_region;
   if (hr != NULL) {
     used += hr->used();
   }
   return used;
 }

 HeapRegion* MutatorAllocRegion::release() {
   HeapRegion* ret = G1AllocRegion::release();

   // The retained alloc region must be retired and this must be
   // done after the above call to release the mutator alloc region,
   // since it might update the _retained_alloc_region member.
   if (_retained_alloc_region != NULL) {
     _wasted_bytes += retire_internal(_retained_alloc_region, false);
     _retained_alloc_region = NULL;
   }
   log_debug(gc, alloc, region)("Mutator Allocation stats, regions: %u, wasted size: " SIZE_FORMAT "%s (%4.1f%%)",
                                count(),
                                byte_size_in_proper_unit(_wasted_bytes),
                                proper_unit_for_byte_size(_wasted_bytes),
                                percent_of(_wasted_bytes, count() * HeapRegion::GrainBytes));
   return ret;
 }

 HeapRegion* G1GCAllocRegion::allocate_new_region(size_t word_size,
                                                  bool force) {
   assert(!force, "not supported for GC alloc regions");
   return _g1h->new_gc_alloc_region(word_size, _purpose);
 }

 void G1GCAllocRegion::retire_region(HeapRegion* alloc_region,
                                     size_t allocated_bytes) {
   _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, _purpose);
 }

 size_t G1GCAllocRegion::retire(bool fill_up) {
   HeapRegion* retired = get();
   size_t end_waste = G1AllocRegion::retire(fill_up);
   // Do not count retirement of the dummy allocation region.
   if (retired != NULL) {
     _stats->add_region_end_waste(end_waste / HeapWordSize);
   }
   return end_waste;
 }

 HeapRegion* OldGCAllocRegion::release() {
   HeapRegion* cur = get();
   if (cur != NULL) {
     // Determine how far we are from the next card boundary. If it is smaller than
     // the minimum object size we can allocate into, expand into the next card.
     HeapWord* top = cur->top();
     HeapWord* aligned_top = align_up(top, BOTConstants::N_bytes);

     size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);

     if (to_allocate_words != 0) {
       // We are not at a card boundary. Fill up, possibly into the next, taking the
       // end of the region and the minimum object size into account.
       to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
                                MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));

       // Skip allocation if there is not enough space to allocate even the smallest
       // possible object. In this case this region will not be retained, so the
       // original problem cannot occur.
       if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
         HeapWord* dummy = attempt_allocation(to_allocate_words);
         CollectedHeap::fill_with_object(dummy, to_allocate_words);
       }
     }
   }
   return G1AllocRegion::release();
 }
	/*
	* Copyright (c) 2011, 2018, 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/g1/g1AllocRegion.inline.hpp"
	#include "gc/g1/g1EvacStats.inline.hpp"
	#include "gc/g1/g1CollectedHeap.inline.hpp"
	#include "logging/log.hpp"
	#include "logging/logStream.hpp"
	#include "memory/resourceArea.hpp"
	#include "runtime/orderAccess.hpp"
	#include "utilities/align.hpp"

	G1CollectedHeap* G1AllocRegion::_g1h = NULL;
	HeapRegion* G1AllocRegion::_dummy_region = NULL;

	void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
	assert(_dummy_region == NULL, "should be set once");
	assert(dummy_region != NULL, "pre-condition");
	assert(dummy_region->free() == 0, "pre-condition");

	// Make sure that any allocation attempt on this region will fail
	// and will not trigger any asserts.
	assert(dummy_region->allocate_no_bot_updates(1) == NULL, "should fail");
	assert(dummy_region->allocate(1) == NULL, "should fail");
	DEBUG_ONLY(size_t assert_tmp);
	assert(dummy_region->par_allocate_no_bot_updates(1, 1, &assert_tmp) == NULL, "should fail");
	assert(dummy_region->par_allocate(1, 1, &assert_tmp) == NULL, "should fail");

	_g1h = g1h;
	_dummy_region = dummy_region;
	}

	size_t G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region) {
	assert(alloc_region != NULL && alloc_region != _dummy_region,
	"pre-condition");
	size_t result = 0;

	// Other threads might still be trying to allocate using a CAS out
	// of the region we are trying to retire, as they can do so without
	// holding the lock. So, we first have to make sure that noone else
	// can allocate out of it by doing a maximal allocation. Even if our
	// CAS attempt fails a few times, we'll succeed sooner or later
	// given that failed CAS attempts mean that the region is getting
	// closed to being full.
	size_t free_word_size = alloc_region->free() / HeapWordSize;

	// This is the minimum free chunk we can turn into a dummy
	// object. If the free space falls below this, then noone can
	// allocate in this region anyway (all allocation requests will be
	// of a size larger than this) so we won't have to perform the dummy
	// allocation.
	size_t min_word_size_to_fill = CollectedHeap::min_fill_size();

	while (free_word_size >= min_word_size_to_fill) {
	HeapWord* dummy = par_allocate(alloc_region, free_word_size);
	if (dummy != NULL) {
	// If the allocation was successful we should fill in the space.
	CollectedHeap::fill_with_object(dummy, free_word_size);
	alloc_region->set_pre_dummy_top(dummy);
	result += free_word_size * HeapWordSize;
	break;
	}

	free_word_size = alloc_region->free() / HeapWordSize;
	// It's also possible that someone else beats us to the
	// allocation and they fill up the region. In that case, we can
	// just get out of the loop.
	}
	result += alloc_region->free();

	assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
	"post-condition");
	return result;
	}

	size_t G1AllocRegion::retire_internal(HeapRegion* alloc_region, bool fill_up) {
	// We never have to check whether the active region is empty or not,
	// and potentially free it if it is, given that it's guaranteed that
	// it will never be empty.
	size_t waste = 0;
	assert_alloc_region(!alloc_region->is_empty(),
	"the alloc region should never be empty");

	if (fill_up) {
	waste = fill_up_remaining_space(alloc_region);
	}

	assert_alloc_region(alloc_region->used() >= _used_bytes_before, "invariant");
	size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
	retire_region(alloc_region, allocated_bytes);
	_used_bytes_before = 0;

	return waste;
	}

	size_t G1AllocRegion::retire(bool fill_up) {
	assert_alloc_region(_alloc_region != NULL, "not initialized properly");

	size_t waste = 0;

	trace("retiring");
	HeapRegion* alloc_region = _alloc_region;
	if (alloc_region != _dummy_region) {
	waste = retire_internal(alloc_region, fill_up);
	reset_alloc_region();
	}
	trace("retired");

	return waste;
	}

	HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
	bool force) {
	assert_alloc_region(_alloc_region == _dummy_region, "pre-condition");
	assert_alloc_region(_used_bytes_before == 0, "pre-condition");

	trace("attempting region allocation");
	HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
	if (new_alloc_region != NULL) {
	new_alloc_region->reset_pre_dummy_top();
	// Need to do this before the allocation
	_used_bytes_before = new_alloc_region->used();
	HeapWord* result = allocate(new_alloc_region, word_size);
	assert_alloc_region(result != NULL, "the allocation should succeeded");

	OrderAccess::storestore();
	// Note that we first perform the allocation and then we store the
	// region in _alloc_region. This is the reason why an active region
	// can never be empty.
	update_alloc_region(new_alloc_region);
	trace("region allocation successful");
	return result;
	} else {
	trace("region allocation failed");
	return NULL;
	}
	ShouldNotReachHere();
	}

	void G1AllocRegion::init() {
	trace("initializing");
	assert_alloc_region(_alloc_region == NULL && _used_bytes_before == 0, "pre-condition");
	assert_alloc_region(_dummy_region != NULL, "should have been set");
	_alloc_region = _dummy_region;
	_count = 0;
	trace("initialized");
	}

	void G1AllocRegion::set(HeapRegion* alloc_region) {
	trace("setting");
	// We explicitly check that the region is not empty to make sure we
	// maintain the "the alloc region cannot be empty" invariant.
	assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");
	assert_alloc_region(_alloc_region == _dummy_region &&
	_used_bytes_before == 0 && _count == 0,
	"pre-condition");

	_used_bytes_before = alloc_region->used();
	_alloc_region = alloc_region;
	_count += 1;
	trace("set");
	}

	void G1AllocRegion::update_alloc_region(HeapRegion* alloc_region) {
	trace("update");
	// We explicitly check that the region is not empty to make sure we
	// maintain the "the alloc region cannot be empty" invariant.
	assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");

	_alloc_region = alloc_region;
	_count += 1;
	trace("updated");
	}

	HeapRegion* G1AllocRegion::release() {
	trace("releasing");
	HeapRegion* alloc_region = _alloc_region;
	retire(false /* fill_up */);
	assert_alloc_region(_alloc_region == _dummy_region, "post-condition of retire()");
	_alloc_region = NULL;
	trace("released");
	return (alloc_region == _dummy_region) ? NULL : alloc_region;
	}

	#ifndef PRODUCT
	void G1AllocRegion::trace(const char* str, size_t min_word_size, size_t desired_word_size, size_t actual_word_size, HeapWord* result) {
	// All the calls to trace that set either just the size or the size
	// and the result are considered part of detailed tracing and are
	// skipped during other tracing.

	Log(gc, alloc, region) log;

	if (!log.is_debug()) {
	return;
	}

	bool detailed_info = log.is_trace();

	if ((actual_word_size == 0 && result == NULL) \|\| detailed_info) {
	ResourceMark rm;
	LogStream ls_trace(log.trace());
	LogStream ls_debug(log.debug());
	outputStream* out = detailed_info ? &ls_trace : &ls_debug;

	out->print("%s: %u ", _name, _count);

	if (_alloc_region == NULL) {
	out->print("NULL");
	} else if (_alloc_region == _dummy_region) {
	out->print("DUMMY");
	} else {
	out->print(HR_FORMAT, HR_FORMAT_PARAMS(_alloc_region));
	}

	out->print(" : %s", str);

	if (detailed_info) {
	if (result != NULL) {
	out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT " actual " SIZE_FORMAT " " PTR_FORMAT,
	min_word_size, desired_word_size, actual_word_size, p2i(result));
	} else if (min_word_size != 0) {
	out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT, min_word_size, desired_word_size);
	}
	}
	out->cr();
	}
	}
	#endif // PRODUCT

	G1AllocRegion::G1AllocRegion(const char* name,
	bool bot_updates)
	: _name(name), _bot_updates(bot_updates),
	_alloc_region(NULL), _count(0),
	_used_bytes_before(0) { }


	HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
	bool force) {
	return _g1h->new_mutator_alloc_region(word_size, force);
	}

	void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
	size_t allocated_bytes) {
	_g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
	}

	void MutatorAllocRegion::init() {
	assert(_retained_alloc_region == NULL, "Pre-condition");
	G1AllocRegion::init();
	_wasted_bytes = 0;
	}

	bool MutatorAllocRegion::should_retain(HeapRegion* region) {
	size_t free_bytes = region->free();
	if (free_bytes < MinTLABSize) {
	return false;
	}

	if (_retained_alloc_region != NULL &&
	free_bytes < _retained_alloc_region->free()) {
	return false;
	}

	return true;
	}

	size_t MutatorAllocRegion::retire(bool fill_up) {
	size_t waste = 0;
	trace("retiring");
	HeapRegion* current_region = get();
	if (current_region != NULL) {
	// Retain the current region if it fits a TLAB and has more
	// free than the currently retained region.
	if (should_retain(current_region)) {
	trace("mutator retained");
	if (_retained_alloc_region != NULL) {
	waste = retire_internal(_retained_alloc_region, true);
	}
	_retained_alloc_region = current_region;
	} else {
	waste = retire_internal(current_region, fill_up);
	}
	reset_alloc_region();
	}

	_wasted_bytes += waste;
	trace("retired");
	return waste;
	}

	size_t MutatorAllocRegion::used_in_alloc_regions() {
	size_t used = 0;
	HeapRegion* hr = get();
	if (hr != NULL) {
	used += hr->used();
	}

	hr = _retained_alloc_region;
	if (hr != NULL) {
	used += hr->used();
	}
	return used;
	}

	HeapRegion* MutatorAllocRegion::release() {
	HeapRegion* ret = G1AllocRegion::release();

	// The retained alloc region must be retired and this must be
	// done after the above call to release the mutator alloc region,
	// since it might update the _retained_alloc_region member.
	if (_retained_alloc_region != NULL) {
	_wasted_bytes += retire_internal(_retained_alloc_region, false);
	_retained_alloc_region = NULL;
	}
	log_debug(gc, alloc, region)("Mutator Allocation stats, regions: %u, wasted size: " SIZE_FORMAT "%s (%4.1f%%)",
	count(),
	byte_size_in_proper_unit(_wasted_bytes),
	proper_unit_for_byte_size(_wasted_bytes),
	percent_of(_wasted_bytes, count() * HeapRegion::GrainBytes));
	return ret;
	}

	HeapRegion* G1GCAllocRegion::allocate_new_region(size_t word_size,
	bool force) {
	assert(!force, "not supported for GC alloc regions");
	return _g1h->new_gc_alloc_region(word_size, _purpose);
	}

	void G1GCAllocRegion::retire_region(HeapRegion* alloc_region,
	size_t allocated_bytes) {
	_g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, _purpose);
	}

	size_t G1GCAllocRegion::retire(bool fill_up) {
	HeapRegion* retired = get();
	size_t end_waste = G1AllocRegion::retire(fill_up);
	// Do not count retirement of the dummy allocation region.
	if (retired != NULL) {
	_stats->add_region_end_waste(end_waste / HeapWordSize);
	}
	return end_waste;
	}

	HeapRegion* OldGCAllocRegion::release() {
	HeapRegion* cur = get();
	if (cur != NULL) {
	// Determine how far we are from the next card boundary. If it is smaller than
	// the minimum object size we can allocate into, expand into the next card.
	HeapWord* top = cur->top();
	HeapWord* aligned_top = align_up(top, BOTConstants::N_bytes);

	size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);

	if (to_allocate_words != 0) {
	// We are not at a card boundary. Fill up, possibly into the next, taking the
	// end of the region and the minimum object size into account.
	to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
	MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));

	// Skip allocation if there is not enough space to allocate even the smallest
	// possible object. In this case this region will not be retained, so the
	// original problem cannot occur.
	if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
	HeapWord* dummy = attempt_allocation(to_allocate_words);
	CollectedHeap::fill_with_object(dummy, to_allocate_words);
	}
	}
	}
	return G1AllocRegion::release();
	}