ysr@777: /*
stefank@2314:  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
ysr@777:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ysr@777:  *
ysr@777:  * This code is free software; you can redistribute it and/or modify it
ysr@777:  * under the terms of the GNU General Public License version 2 only, as
ysr@777:  * published by the Free Software Foundation.
ysr@777:  *
ysr@777:  * This code is distributed in the hope that it will be useful, but WITHOUT
ysr@777:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ysr@777:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ysr@777:  * version 2 for more details (a copy is included in the LICENSE file that
ysr@777:  * accompanied this code).
ysr@777:  *
ysr@777:  * You should have received a copy of the GNU General Public License version
ysr@777:  * 2 along with this work; if not, write to the Free Software Foundation,
ysr@777:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ysr@777:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
ysr@777:  *
ysr@777:  */
ysr@777: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "gc_implementation/g1/g1MMUTracker.hpp"
stefank@2314: #include "runtime/mutexLocker.hpp"
stefank@2314: #include "utilities/ostream.hpp"
ysr@777: 
ysr@777: #define _DISABLE_MMU                             0
ysr@777: 
ysr@777: // can't rely on comparing doubles with tolerating a small margin for error
ysr@777: #define SMALL_MARGIN 0.0000001
ysr@777: #define is_double_leq_0(_value) ( (_value) < SMALL_MARGIN )
ysr@777: #define is_double_leq(_val1, _val2) is_double_leq_0((_val1) - (_val2))
ysr@777: #define is_double_geq(_val1, _val2) is_double_leq_0((_val2) - (_val1))
ysr@777: 
ysr@777: /***** ALL TIMES ARE IN SECS!!!!!!! *****/
ysr@777: 
ysr@777: G1MMUTracker::G1MMUTracker(double time_slice, double max_gc_time) :
ysr@777:   _time_slice(time_slice),
tonyp@1371:   _max_gc_time(max_gc_time) { }
ysr@777: 
ysr@777: G1MMUTrackerQueue::G1MMUTrackerQueue(double time_slice, double max_gc_time) :
ysr@777:   G1MMUTracker(time_slice, max_gc_time),
ysr@777:   _head_index(0),
ysr@777:   _tail_index(trim_index(_head_index+1)),
ysr@777:   _no_entries(0) { }
ysr@777: 
ysr@777: void G1MMUTrackerQueue::remove_expired_entries(double current_time) {
ysr@777:   double limit = current_time - _time_slice;
ysr@777:   while (_no_entries > 0) {
ysr@777:     if (is_double_geq(limit, _array[_tail_index].end_time())) {
ysr@777:       _tail_index = trim_index(_tail_index + 1);
ysr@777:       --_no_entries;
ysr@777:     } else
ysr@777:       return;
ysr@777:   }
ysr@777:   guarantee(_no_entries == 0, "should have no entries in the array");
ysr@777: }
ysr@777: 
ysr@777: double G1MMUTrackerQueue::calculate_gc_time(double current_time) {
ysr@777:   double gc_time = 0.0;
ysr@777:   double limit = current_time - _time_slice;
ysr@777:   for (int i = 0; i < _no_entries; ++i) {
ysr@777:     int index = trim_index(_tail_index + i);
ysr@777:     G1MMUTrackerQueueElem *elem = &_array[index];
ysr@777:     if (elem->end_time() > limit) {
ysr@777:       if (elem->start_time() > limit)
ysr@777:         gc_time += elem->duration();
ysr@777:       else
ysr@777:         gc_time += elem->end_time() - limit;
ysr@777:     }
ysr@777:   }
ysr@777:   return gc_time;
ysr@777: }
ysr@777: 
ysr@777: void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) {
ysr@777:   double longest_allowed = longest_pause_internal(start);
ysr@777:   if (longest_allowed < 0.0)
ysr@777:     longest_allowed = 0.0;
ysr@777:   double duration = end - start;
ysr@777: 
ysr@777:   remove_expired_entries(end);
ysr@777:   if (_no_entries == QueueLength) {
johnc@1946:     // OK, we've filled up the queue. There are a few ways
johnc@1946:     // of dealing with this "gracefully"
ysr@777:     //   increase the array size (:-)
ysr@777:     //   remove the oldest entry (this might allow more GC time for
johnc@1946:     //     the time slice than what's allowed) - this is what we
johnc@1946:     //     currently do
ysr@1523:     //   consolidate the two entries with the minimum gap between them
ysr@1523:     //     (this might allow less GC time than what's allowed)
johnc@1946: 
ysr@1523:     // In the case where ScavengeALot is true, such overflow is not
ysr@1523:     // uncommon; in such cases, we can, without much loss of precision
ysr@1523:     // or performance (we are GC'ing most of the time anyway!),
johnc@1946:     // simply overwrite the oldest entry in the tracker.
johnc@1946: 
johnc@1946:     if (G1PolicyVerbose > 1) {
johnc@1946:       warning("MMU Tracker Queue overflow. Replacing earliest entry.");
johnc@1946:     }
johnc@1946: 
ysr@1523:     _head_index = trim_index(_head_index + 1);
ysr@1523:     assert(_head_index == _tail_index, "Because we have a full circular buffer");
ysr@1523:     _tail_index = trim_index(_tail_index + 1);
ysr@1523:   } else {
ysr@1523:     _head_index = trim_index(_head_index + 1);
ysr@1523:     ++_no_entries;
ysr@777:   }
ysr@777:   _array[_head_index] = G1MMUTrackerQueueElem(start, end);
ysr@777: }
ysr@777: 
ysr@777: // basically the _internal call does not remove expired entries
ysr@777: // this is for trying things out in the future and a couple
ysr@777: // of other places (debugging)
ysr@777: 
ysr@777: double G1MMUTrackerQueue::longest_pause(double current_time) {
ysr@777:   if (_DISABLE_MMU)
ysr@777:     return _max_gc_time;
ysr@777: 
ysr@777:   MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag);
ysr@777:   remove_expired_entries(current_time);
ysr@777: 
ysr@777:   return longest_pause_internal(current_time);
ysr@777: }
ysr@777: 
ysr@777: double G1MMUTrackerQueue::longest_pause_internal(double current_time) {
ysr@777:   double target_time = _max_gc_time;
ysr@777: 
ysr@777:   while( 1 ) {
ysr@777:     double gc_time =
tonyp@1371:       calculate_gc_time(current_time + target_time);
ysr@777:     double diff = target_time + gc_time - _max_gc_time;
ysr@777:     if (!is_double_leq_0(diff)) {
ysr@777:       target_time -= diff;
ysr@777:       if (is_double_leq_0(target_time)) {
ysr@777:         target_time = -1.0;
ysr@777:         break;
ysr@777:       }
ysr@777:     } else {
ysr@777:       break;
ysr@777:     }
ysr@777:   }
ysr@777: 
ysr@777:   return target_time;
ysr@777: }
ysr@777: 
ysr@777: // basically the _internal call does not remove expired entries
ysr@777: // this is for trying things out in the future and a couple
ysr@777: // of other places (debugging)
ysr@777: 
ysr@777: double G1MMUTrackerQueue::when_sec(double current_time, double pause_time) {
ysr@777:   if (_DISABLE_MMU)
ysr@777:     return 0.0;
ysr@777: 
ysr@777:   MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag);
ysr@777:   remove_expired_entries(current_time);
ysr@777: 
ysr@777:   return when_internal(current_time, pause_time);
ysr@777: }
ysr@777: 
ysr@777: double G1MMUTrackerQueue::when_internal(double current_time,
ysr@777:                                         double pause_time) {
ysr@777:   // if the pause is over the maximum, just assume that it's the maximum
ysr@777:   double adjusted_pause_time =
ysr@777:     (pause_time > max_gc_time()) ? max_gc_time() : pause_time;
ysr@777:   double earliest_end = current_time + adjusted_pause_time;
ysr@777:   double limit = earliest_end - _time_slice;
ysr@777:   double gc_time = calculate_gc_time(earliest_end);
ysr@777:   double diff = gc_time + adjusted_pause_time - max_gc_time();
ysr@777:   if (is_double_leq_0(diff))
ysr@777:     return 0.0;
ysr@777: 
ysr@777:   int index = _tail_index;
ysr@777:   while ( 1 ) {
ysr@777:     G1MMUTrackerQueueElem *elem = &_array[index];
ysr@777:     if (elem->end_time() > limit) {
ysr@777:       if (elem->start_time() > limit)
ysr@777:         diff -= elem->duration();
ysr@777:       else
ysr@777:         diff -= elem->end_time() - limit;
ysr@777:       if (is_double_leq_0(diff))
ysr@777:         return  elem->end_time() + diff + _time_slice - adjusted_pause_time - current_time;
ysr@777:     }
ysr@777:     index = trim_index(index+1);
ysr@777:     guarantee(index != trim_index(_head_index + 1), "should not go past head");
ysr@777:   }
ysr@777: }