311 lines
12 KiB
C++
311 lines
12 KiB
C++
/*
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* Copyright (c) 2011, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "gc/g1/g1AllocRegion.inline.hpp"
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#include "gc/g1/g1EvacStats.inline.hpp"
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#include "gc/g1/g1CollectedHeap.inline.hpp"
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#include "memory/resourceArea.hpp"
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#include "runtime/orderAccess.inline.hpp"
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G1CollectedHeap* G1AllocRegion::_g1h = NULL;
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HeapRegion* G1AllocRegion::_dummy_region = NULL;
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void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
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assert(_dummy_region == NULL, "should be set once");
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assert(dummy_region != NULL, "pre-condition");
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assert(dummy_region->free() == 0, "pre-condition");
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// Make sure that any allocation attempt on this region will fail
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// and will not trigger any asserts.
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assert(allocate(dummy_region, 1, false) == NULL, "should fail");
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assert(par_allocate(dummy_region, 1, false) == NULL, "should fail");
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assert(allocate(dummy_region, 1, true) == NULL, "should fail");
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assert(par_allocate(dummy_region, 1, true) == NULL, "should fail");
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_g1h = g1h;
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_dummy_region = dummy_region;
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}
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size_t G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region,
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bool bot_updates) {
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assert(alloc_region != NULL && alloc_region != _dummy_region,
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"pre-condition");
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size_t result = 0;
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// Other threads might still be trying to allocate using a CAS out
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// of the region we are trying to retire, as they can do so without
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// holding the lock. So, we first have to make sure that noone else
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// can allocate out of it by doing a maximal allocation. Even if our
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// CAS attempt fails a few times, we'll succeed sooner or later
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// given that failed CAS attempts mean that the region is getting
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// closed to being full.
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size_t free_word_size = alloc_region->free() / HeapWordSize;
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// This is the minimum free chunk we can turn into a dummy
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// object. If the free space falls below this, then noone can
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// allocate in this region anyway (all allocation requests will be
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// of a size larger than this) so we won't have to perform the dummy
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// allocation.
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size_t min_word_size_to_fill = CollectedHeap::min_fill_size();
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while (free_word_size >= min_word_size_to_fill) {
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HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates);
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if (dummy != NULL) {
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// If the allocation was successful we should fill in the space.
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CollectedHeap::fill_with_object(dummy, free_word_size);
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alloc_region->set_pre_dummy_top(dummy);
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result += free_word_size * HeapWordSize;
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break;
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}
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free_word_size = alloc_region->free() / HeapWordSize;
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// It's also possible that someone else beats us to the
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// allocation and they fill up the region. In that case, we can
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// just get out of the loop.
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}
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result += alloc_region->free();
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assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
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"post-condition");
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return result;
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}
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size_t G1AllocRegion::retire(bool fill_up) {
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assert_alloc_region(_alloc_region != NULL, "not initialized properly");
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size_t result = 0;
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trace("retiring");
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HeapRegion* alloc_region = _alloc_region;
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if (alloc_region != _dummy_region) {
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// We never have to check whether the active region is empty or not,
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// and potentially free it if it is, given that it's guaranteed that
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// it will never be empty.
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assert_alloc_region(!alloc_region->is_empty(),
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"the alloc region should never be empty");
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if (fill_up) {
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result = fill_up_remaining_space(alloc_region, _bot_updates);
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}
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assert_alloc_region(alloc_region->used() >= _used_bytes_before, "invariant");
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size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
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retire_region(alloc_region, allocated_bytes);
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_used_bytes_before = 0;
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_alloc_region = _dummy_region;
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}
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trace("retired");
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return result;
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}
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HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
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bool force) {
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assert_alloc_region(_alloc_region == _dummy_region, "pre-condition");
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assert_alloc_region(_used_bytes_before == 0, "pre-condition");
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trace("attempting region allocation");
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HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
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if (new_alloc_region != NULL) {
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new_alloc_region->reset_pre_dummy_top();
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// Need to do this before the allocation
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_used_bytes_before = new_alloc_region->used();
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HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates);
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assert_alloc_region(result != NULL, "the allocation should succeeded");
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OrderAccess::storestore();
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// Note that we first perform the allocation and then we store the
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// region in _alloc_region. This is the reason why an active region
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// can never be empty.
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update_alloc_region(new_alloc_region);
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trace("region allocation successful");
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return result;
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} else {
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trace("region allocation failed");
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return NULL;
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}
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ShouldNotReachHere();
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}
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void G1AllocRegion::init() {
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trace("initializing");
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assert_alloc_region(_alloc_region == NULL && _used_bytes_before == 0, "pre-condition");
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assert_alloc_region(_dummy_region != NULL, "should have been set");
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_alloc_region = _dummy_region;
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_count = 0;
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trace("initialized");
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}
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void G1AllocRegion::set(HeapRegion* alloc_region) {
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trace("setting");
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// We explicitly check that the region is not empty to make sure we
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// maintain the "the alloc region cannot be empty" invariant.
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assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");
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assert_alloc_region(_alloc_region == _dummy_region &&
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_used_bytes_before == 0 && _count == 0,
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"pre-condition");
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_used_bytes_before = alloc_region->used();
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_alloc_region = alloc_region;
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_count += 1;
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trace("set");
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}
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void G1AllocRegion::update_alloc_region(HeapRegion* alloc_region) {
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trace("update");
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// We explicitly check that the region is not empty to make sure we
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// maintain the "the alloc region cannot be empty" invariant.
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assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");
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_alloc_region = alloc_region;
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_alloc_region->set_allocation_context(allocation_context());
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_count += 1;
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trace("updated");
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}
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HeapRegion* G1AllocRegion::release() {
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trace("releasing");
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HeapRegion* alloc_region = _alloc_region;
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retire(false /* fill_up */);
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assert_alloc_region(_alloc_region == _dummy_region, "post-condition of retire()");
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_alloc_region = NULL;
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trace("released");
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return (alloc_region == _dummy_region) ? NULL : alloc_region;
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}
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#ifndef PRODUCT
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void G1AllocRegion::trace(const char* str, size_t min_word_size, size_t desired_word_size, size_t actual_word_size, HeapWord* result) {
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// All the calls to trace that set either just the size or the size
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// and the result are considered part of detailed tracing and are
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// skipped during other tracing.
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LogHandle(gc, alloc, region) log;
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if (!log.is_debug()) {
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return;
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}
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bool detailed_info = log.is_trace();
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if ((actual_word_size == 0 && result == NULL) || detailed_info) {
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ResourceMark rm;
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outputStream* out;
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if (detailed_info) {
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out = log.trace_stream();
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} else {
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out = log.debug_stream();
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}
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out->print("%s: %u ", _name, _count);
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if (_alloc_region == NULL) {
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out->print("NULL");
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} else if (_alloc_region == _dummy_region) {
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out->print("DUMMY");
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} else {
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out->print(HR_FORMAT, HR_FORMAT_PARAMS(_alloc_region));
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}
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out->print(" : %s", str);
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if (detailed_info) {
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if (result != NULL) {
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out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT " actual " SIZE_FORMAT " " PTR_FORMAT,
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min_word_size, desired_word_size, actual_word_size, p2i(result));
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} else if (min_word_size != 0) {
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out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT, min_word_size, desired_word_size);
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}
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}
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out->cr();
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}
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}
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#endif // PRODUCT
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G1AllocRegion::G1AllocRegion(const char* name,
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bool bot_updates)
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: _name(name), _bot_updates(bot_updates),
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_alloc_region(NULL), _count(0), _used_bytes_before(0),
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_allocation_context(AllocationContext::system()) { }
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HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
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bool force) {
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return _g1h->new_mutator_alloc_region(word_size, force);
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}
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void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
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size_t allocated_bytes) {
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_g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
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}
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HeapRegion* G1GCAllocRegion::allocate_new_region(size_t word_size,
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bool force) {
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assert(!force, "not supported for GC alloc regions");
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return _g1h->new_gc_alloc_region(word_size, _purpose);
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}
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void G1GCAllocRegion::retire_region(HeapRegion* alloc_region,
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size_t allocated_bytes) {
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_g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, _purpose);
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}
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size_t G1GCAllocRegion::retire(bool fill_up) {
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HeapRegion* retired = get();
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size_t end_waste = G1AllocRegion::retire(fill_up);
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// Do not count retirement of the dummy allocation region.
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if (retired != NULL) {
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_stats->add_region_end_waste(end_waste / HeapWordSize);
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}
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return end_waste;
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}
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HeapRegion* OldGCAllocRegion::release() {
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HeapRegion* cur = get();
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if (cur != NULL) {
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// Determine how far we are from the next card boundary. If it is smaller than
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// the minimum object size we can allocate into, expand into the next card.
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HeapWord* top = cur->top();
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HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, BOTConstants::N_bytes);
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size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
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if (to_allocate_words != 0) {
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// We are not at a card boundary. Fill up, possibly into the next, taking the
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// end of the region and the minimum object size into account.
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to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
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MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
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// Skip allocation if there is not enough space to allocate even the smallest
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// possible object. In this case this region will not be retained, so the
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// original problem cannot occur.
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if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
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HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */);
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CollectedHeap::fill_with_object(dummy, to_allocate_words);
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}
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}
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}
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return G1AllocRegion::release();
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}
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