| /* |
| * Copyright (c) 2011, 2016, 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.inline.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(allocate(dummy_region, 1, false) == NULL, "should fail"); |
| assert(par_allocate(dummy_region, 1, false) == NULL, "should fail"); |
| assert(allocate(dummy_region, 1, true) == NULL, "should fail"); |
| assert(par_allocate(dummy_region, 1, true) == NULL, "should fail"); |
| |
| _g1h = g1h; |
| _dummy_region = dummy_region; |
| } |
| |
| size_t G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region, |
| bool bot_updates) { |
| 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, bot_updates); |
| 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(bool fill_up) { |
| assert_alloc_region(_alloc_region != NULL, "not initialized properly"); |
| |
| size_t result = 0; |
| |
| trace("retiring"); |
| HeapRegion* alloc_region = _alloc_region; |
| if (alloc_region != _dummy_region) { |
| // 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. |
| assert_alloc_region(!alloc_region->is_empty(), |
| "the alloc region should never be empty"); |
| |
| if (fill_up) { |
| result = fill_up_remaining_space(alloc_region, _bot_updates); |
| } |
| |
| 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; |
| _alloc_region = _dummy_region; |
| } |
| trace("retired"); |
| |
| return result; |
| } |
| |
| 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, _bot_updates); |
| 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; |
| _alloc_region->set_allocation_context(allocation_context()); |
| _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), |
| _allocation_context(AllocationContext::system()) { } |
| |
| |
| 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); |
| } |
| |
| 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, true /* bot_updates */); |
| CollectedHeap::fill_with_object(dummy, to_allocate_words); |
| } |
| } |
| } |
| return G1AllocRegion::release(); |
| } |