1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/g1/g1AllocRegion.cpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,228 @@
1.4 +/*
1.5 + * Copyright (c) 2011, 2014, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "precompiled.hpp"
1.29 +#include "gc_implementation/g1/g1AllocRegion.inline.hpp"
1.30 +#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
1.31 +
1.32 +G1CollectedHeap* G1AllocRegion::_g1h = NULL;
1.33 +HeapRegion* G1AllocRegion::_dummy_region = NULL;
1.34 +
1.35 +void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
1.36 + assert(_dummy_region == NULL, "should be set once");
1.37 + assert(dummy_region != NULL, "pre-condition");
1.38 + assert(dummy_region->free() == 0, "pre-condition");
1.39 +
1.40 + // Make sure that any allocation attempt on this region will fail
1.41 + // and will not trigger any asserts.
1.42 + assert(allocate(dummy_region, 1, false) == NULL, "should fail");
1.43 + assert(par_allocate(dummy_region, 1, false) == NULL, "should fail");
1.44 + assert(allocate(dummy_region, 1, true) == NULL, "should fail");
1.45 + assert(par_allocate(dummy_region, 1, true) == NULL, "should fail");
1.46 +
1.47 + _g1h = g1h;
1.48 + _dummy_region = dummy_region;
1.49 +}
1.50 +
1.51 +void G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region,
1.52 + bool bot_updates) {
1.53 + assert(alloc_region != NULL && alloc_region != _dummy_region,
1.54 + "pre-condition");
1.55 +
1.56 + // Other threads might still be trying to allocate using a CAS out
1.57 + // of the region we are trying to retire, as they can do so without
1.58 + // holding the lock. So, we first have to make sure that noone else
1.59 + // can allocate out of it by doing a maximal allocation. Even if our
1.60 + // CAS attempt fails a few times, we'll succeed sooner or later
1.61 + // given that failed CAS attempts mean that the region is getting
1.62 + // closed to being full.
1.63 + size_t free_word_size = alloc_region->free() / HeapWordSize;
1.64 +
1.65 + // This is the minimum free chunk we can turn into a dummy
1.66 + // object. If the free space falls below this, then noone can
1.67 + // allocate in this region anyway (all allocation requests will be
1.68 + // of a size larger than this) so we won't have to perform the dummy
1.69 + // allocation.
1.70 + size_t min_word_size_to_fill = CollectedHeap::min_fill_size();
1.71 +
1.72 + while (free_word_size >= min_word_size_to_fill) {
1.73 + HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates);
1.74 + if (dummy != NULL) {
1.75 + // If the allocation was successful we should fill in the space.
1.76 + CollectedHeap::fill_with_object(dummy, free_word_size);
1.77 + alloc_region->set_pre_dummy_top(dummy);
1.78 + break;
1.79 + }
1.80 +
1.81 + free_word_size = alloc_region->free() / HeapWordSize;
1.82 + // It's also possible that someone else beats us to the
1.83 + // allocation and they fill up the region. In that case, we can
1.84 + // just get out of the loop.
1.85 + }
1.86 + assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
1.87 + "post-condition");
1.88 +}
1.89 +
1.90 +void G1AllocRegion::retire(bool fill_up) {
1.91 + assert(_alloc_region != NULL, ar_ext_msg(this, "not initialized properly"));
1.92 +
1.93 + trace("retiring");
1.94 + HeapRegion* alloc_region = _alloc_region;
1.95 + if (alloc_region != _dummy_region) {
1.96 + // We never have to check whether the active region is empty or not,
1.97 + // and potentially free it if it is, given that it's guaranteed that
1.98 + // it will never be empty.
1.99 + assert(!alloc_region->is_empty(),
1.100 + ar_ext_msg(this, "the alloc region should never be empty"));
1.101 +
1.102 + if (fill_up) {
1.103 + fill_up_remaining_space(alloc_region, _bot_updates);
1.104 + }
1.105 +
1.106 + assert(alloc_region->used() >= _used_bytes_before,
1.107 + ar_ext_msg(this, "invariant"));
1.108 + size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
1.109 + retire_region(alloc_region, allocated_bytes);
1.110 + _used_bytes_before = 0;
1.111 + _alloc_region = _dummy_region;
1.112 + }
1.113 + trace("retired");
1.114 +}
1.115 +
1.116 +HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
1.117 + bool force) {
1.118 + assert(_alloc_region == _dummy_region, ar_ext_msg(this, "pre-condition"));
1.119 + assert(_used_bytes_before == 0, ar_ext_msg(this, "pre-condition"));
1.120 +
1.121 + trace("attempting region allocation");
1.122 + HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
1.123 + if (new_alloc_region != NULL) {
1.124 + new_alloc_region->reset_pre_dummy_top();
1.125 + // Need to do this before the allocation
1.126 + _used_bytes_before = new_alloc_region->used();
1.127 + HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates);
1.128 + assert(result != NULL, ar_ext_msg(this, "the allocation should succeeded"));
1.129 +
1.130 + OrderAccess::storestore();
1.131 + // Note that we first perform the allocation and then we store the
1.132 + // region in _alloc_region. This is the reason why an active region
1.133 + // can never be empty.
1.134 + _alloc_region = new_alloc_region;
1.135 + _count += 1;
1.136 + trace("region allocation successful");
1.137 + return result;
1.138 + } else {
1.139 + trace("region allocation failed");
1.140 + return NULL;
1.141 + }
1.142 + ShouldNotReachHere();
1.143 +}
1.144 +
1.145 +void G1AllocRegion::fill_in_ext_msg(ar_ext_msg* msg, const char* message) {
1.146 + msg->append("[%s] %s c: %u b: %s r: "PTR_FORMAT" u: "SIZE_FORMAT,
1.147 + _name, message, _count, BOOL_TO_STR(_bot_updates),
1.148 + p2i(_alloc_region), _used_bytes_before);
1.149 +}
1.150 +
1.151 +void G1AllocRegion::init() {
1.152 + trace("initializing");
1.153 + assert(_alloc_region == NULL && _used_bytes_before == 0,
1.154 + ar_ext_msg(this, "pre-condition"));
1.155 + assert(_dummy_region != NULL, ar_ext_msg(this, "should have been set"));
1.156 + _alloc_region = _dummy_region;
1.157 + _count = 0;
1.158 + trace("initialized");
1.159 +}
1.160 +
1.161 +void G1AllocRegion::set(HeapRegion* alloc_region) {
1.162 + trace("setting");
1.163 + // We explicitly check that the region is not empty to make sure we
1.164 + // maintain the "the alloc region cannot be empty" invariant.
1.165 + assert(alloc_region != NULL && !alloc_region->is_empty(),
1.166 + ar_ext_msg(this, "pre-condition"));
1.167 + assert(_alloc_region == _dummy_region &&
1.168 + _used_bytes_before == 0 && _count == 0,
1.169 + ar_ext_msg(this, "pre-condition"));
1.170 +
1.171 + _used_bytes_before = alloc_region->used();
1.172 + _alloc_region = alloc_region;
1.173 + _count += 1;
1.174 + trace("set");
1.175 +}
1.176 +
1.177 +HeapRegion* G1AllocRegion::release() {
1.178 + trace("releasing");
1.179 + HeapRegion* alloc_region = _alloc_region;
1.180 + retire(false /* fill_up */);
1.181 + assert(_alloc_region == _dummy_region,
1.182 + ar_ext_msg(this, "post-condition of retire()"));
1.183 + _alloc_region = NULL;
1.184 + trace("released");
1.185 + return (alloc_region == _dummy_region) ? NULL : alloc_region;
1.186 +}
1.187 +
1.188 +#if G1_ALLOC_REGION_TRACING
1.189 +void G1AllocRegion::trace(const char* str, size_t word_size, HeapWord* result) {
1.190 + // All the calls to trace that set either just the size or the size
1.191 + // and the result are considered part of level 2 tracing and are
1.192 + // skipped during level 1 tracing.
1.193 + if ((word_size == 0 && result == NULL) || (G1_ALLOC_REGION_TRACING > 1)) {
1.194 + const size_t buffer_length = 128;
1.195 + char hr_buffer[buffer_length];
1.196 + char rest_buffer[buffer_length];
1.197 +
1.198 + HeapRegion* alloc_region = _alloc_region;
1.199 + if (alloc_region == NULL) {
1.200 + jio_snprintf(hr_buffer, buffer_length, "NULL");
1.201 + } else if (alloc_region == _dummy_region) {
1.202 + jio_snprintf(hr_buffer, buffer_length, "DUMMY");
1.203 + } else {
1.204 + jio_snprintf(hr_buffer, buffer_length,
1.205 + HR_FORMAT, HR_FORMAT_PARAMS(alloc_region));
1.206 + }
1.207 +
1.208 + if (G1_ALLOC_REGION_TRACING > 1) {
1.209 + if (result != NULL) {
1.210 + jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT" "PTR_FORMAT,
1.211 + word_size, result);
1.212 + } else if (word_size != 0) {
1.213 + jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT, word_size);
1.214 + } else {
1.215 + jio_snprintf(rest_buffer, buffer_length, "");
1.216 + }
1.217 + } else {
1.218 + jio_snprintf(rest_buffer, buffer_length, "");
1.219 + }
1.220 +
1.221 + tty->print_cr("[%s] %u %s : %s %s",
1.222 + _name, _count, hr_buffer, str, rest_buffer);
1.223 + }
1.224 +}
1.225 +#endif // G1_ALLOC_REGION_TRACING
1.226 +
1.227 +G1AllocRegion::G1AllocRegion(const char* name,
1.228 + bool bot_updates)
1.229 + : _name(name), _bot_updates(bot_updates),
1.230 + _alloc_region(NULL), _count(0), _used_bytes_before(0) { }
1.231 +
