1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/g1/g1MMUTracker.cpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,185 @@
1.4 +/*
1.5 + * Copyright (c) 2001, 2011, 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/g1MMUTracker.hpp"
1.30 +#include "runtime/mutexLocker.hpp"
1.31 +#include "utilities/ostream.hpp"
1.32 +
1.33 +#define _DISABLE_MMU 0
1.34 +
1.35 +// can't rely on comparing doubles with tolerating a small margin for error
1.36 +#define SMALL_MARGIN 0.0000001
1.37 +#define is_double_leq_0(_value) ( (_value) < SMALL_MARGIN )
1.38 +#define is_double_leq(_val1, _val2) is_double_leq_0((_val1) - (_val2))
1.39 +#define is_double_geq(_val1, _val2) is_double_leq_0((_val2) - (_val1))
1.40 +
1.41 +/***** ALL TIMES ARE IN SECS!!!!!!! *****/
1.42 +
1.43 +G1MMUTracker::G1MMUTracker(double time_slice, double max_gc_time) :
1.44 + _time_slice(time_slice),
1.45 + _max_gc_time(max_gc_time) { }
1.46 +
1.47 +G1MMUTrackerQueue::G1MMUTrackerQueue(double time_slice, double max_gc_time) :
1.48 + G1MMUTracker(time_slice, max_gc_time),
1.49 + _head_index(0),
1.50 + _tail_index(trim_index(_head_index+1)),
1.51 + _no_entries(0) { }
1.52 +
1.53 +void G1MMUTrackerQueue::remove_expired_entries(double current_time) {
1.54 + double limit = current_time - _time_slice;
1.55 + while (_no_entries > 0) {
1.56 + if (is_double_geq(limit, _array[_tail_index].end_time())) {
1.57 + _tail_index = trim_index(_tail_index + 1);
1.58 + --_no_entries;
1.59 + } else
1.60 + return;
1.61 + }
1.62 + guarantee(_no_entries == 0, "should have no entries in the array");
1.63 +}
1.64 +
1.65 +double G1MMUTrackerQueue::calculate_gc_time(double current_time) {
1.66 + double gc_time = 0.0;
1.67 + double limit = current_time - _time_slice;
1.68 + for (int i = 0; i < _no_entries; ++i) {
1.69 + int index = trim_index(_tail_index + i);
1.70 + G1MMUTrackerQueueElem *elem = &_array[index];
1.71 + if (elem->end_time() > limit) {
1.72 + if (elem->start_time() > limit)
1.73 + gc_time += elem->duration();
1.74 + else
1.75 + gc_time += elem->end_time() - limit;
1.76 + }
1.77 + }
1.78 + return gc_time;
1.79 +}
1.80 +
1.81 +void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) {
1.82 + double longest_allowed = longest_pause_internal(start);
1.83 + if (longest_allowed < 0.0)
1.84 + longest_allowed = 0.0;
1.85 + double duration = end - start;
1.86 +
1.87 + remove_expired_entries(end);
1.88 + if (_no_entries == QueueLength) {
1.89 + // OK, we've filled up the queue. There are a few ways
1.90 + // of dealing with this "gracefully"
1.91 + // increase the array size (:-)
1.92 + // remove the oldest entry (this might allow more GC time for
1.93 + // the time slice than what's allowed) - this is what we
1.94 + // currently do
1.95 + // consolidate the two entries with the minimum gap between them
1.96 + // (this might allow less GC time than what's allowed)
1.97 +
1.98 + // In the case where ScavengeALot is true, such overflow is not
1.99 + // uncommon; in such cases, we can, without much loss of precision
1.100 + // or performance (we are GC'ing most of the time anyway!),
1.101 + // simply overwrite the oldest entry in the tracker.
1.102 +
1.103 + _head_index = trim_index(_head_index + 1);
1.104 + assert(_head_index == _tail_index, "Because we have a full circular buffer");
1.105 + _tail_index = trim_index(_tail_index + 1);
1.106 + } else {
1.107 + _head_index = trim_index(_head_index + 1);
1.108 + ++_no_entries;
1.109 + }
1.110 + _array[_head_index] = G1MMUTrackerQueueElem(start, end);
1.111 +}
1.112 +
1.113 +// basically the _internal call does not remove expired entries
1.114 +// this is for trying things out in the future and a couple
1.115 +// of other places (debugging)
1.116 +
1.117 +double G1MMUTrackerQueue::longest_pause(double current_time) {
1.118 + if (_DISABLE_MMU)
1.119 + return _max_gc_time;
1.120 +
1.121 + MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag);
1.122 + remove_expired_entries(current_time);
1.123 +
1.124 + return longest_pause_internal(current_time);
1.125 +}
1.126 +
1.127 +double G1MMUTrackerQueue::longest_pause_internal(double current_time) {
1.128 + double target_time = _max_gc_time;
1.129 +
1.130 + while( 1 ) {
1.131 + double gc_time =
1.132 + calculate_gc_time(current_time + target_time);
1.133 + double diff = target_time + gc_time - _max_gc_time;
1.134 + if (!is_double_leq_0(diff)) {
1.135 + target_time -= diff;
1.136 + if (is_double_leq_0(target_time)) {
1.137 + target_time = -1.0;
1.138 + break;
1.139 + }
1.140 + } else {
1.141 + break;
1.142 + }
1.143 + }
1.144 +
1.145 + return target_time;
1.146 +}
1.147 +
1.148 +// basically the _internal call does not remove expired entries
1.149 +// this is for trying things out in the future and a couple
1.150 +// of other places (debugging)
1.151 +
1.152 +double G1MMUTrackerQueue::when_sec(double current_time, double pause_time) {
1.153 + if (_DISABLE_MMU)
1.154 + return 0.0;
1.155 +
1.156 + MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag);
1.157 + remove_expired_entries(current_time);
1.158 +
1.159 + return when_internal(current_time, pause_time);
1.160 +}
1.161 +
1.162 +double G1MMUTrackerQueue::when_internal(double current_time,
1.163 + double pause_time) {
1.164 + // if the pause is over the maximum, just assume that it's the maximum
1.165 + double adjusted_pause_time =
1.166 + (pause_time > max_gc_time()) ? max_gc_time() : pause_time;
1.167 + double earliest_end = current_time + adjusted_pause_time;
1.168 + double limit = earliest_end - _time_slice;
1.169 + double gc_time = calculate_gc_time(earliest_end);
1.170 + double diff = gc_time + adjusted_pause_time - max_gc_time();
1.171 + if (is_double_leq_0(diff))
1.172 + return 0.0;
1.173 +
1.174 + int index = _tail_index;
1.175 + while ( 1 ) {
1.176 + G1MMUTrackerQueueElem *elem = &_array[index];
1.177 + if (elem->end_time() > limit) {
1.178 + if (elem->start_time() > limit)
1.179 + diff -= elem->duration();
1.180 + else
1.181 + diff -= elem->end_time() - limit;
1.182 + if (is_double_leq_0(diff))
1.183 + return elem->end_time() + diff + _time_slice - adjusted_pause_time - current_time;
1.184 + }
1.185 + index = trim_index(index+1);
1.186 + guarantee(index != trim_index(_head_index + 1), "should not go past head");
1.187 + }
1.188 +}
