/* * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ #include "incls/_precompiled.incl" #include "incls/_g1MMUTracker.cpp.incl" #define _DISABLE_MMU 0 // can't rely on comparing doubles with tolerating a small margin for error #define SMALL_MARGIN 0.0000001 #define is_double_leq_0(_value) ( (_value) < SMALL_MARGIN ) #define is_double_leq(_val1, _val2) is_double_leq_0((_val1) - (_val2)) #define is_double_geq(_val1, _val2) is_double_leq_0((_val2) - (_val1)) /***** ALL TIMES ARE IN SECS!!!!!!! *****/ G1MMUTracker::G1MMUTracker(double time_slice, double max_gc_time) : _time_slice(time_slice), _max_gc_time(max_gc_time), _conc_overhead_time_sec(0.0) { } void G1MMUTracker::update_conc_overhead(double conc_overhead) { double conc_overhead_time_sec = _time_slice * conc_overhead; if (conc_overhead_time_sec > 0.9 * _max_gc_time) { // We are screwed, as we only seem to have <10% of the soft // real-time goal available for pauses. Let's admit defeat and // allow something more generous as a pause target. conc_overhead_time_sec = 0.75 * _max_gc_time; } _conc_overhead_time_sec = conc_overhead_time_sec; } G1MMUTrackerQueue::G1MMUTrackerQueue(double time_slice, double max_gc_time) : G1MMUTracker(time_slice, max_gc_time), _head_index(0), _tail_index(trim_index(_head_index+1)), _no_entries(0) { } void G1MMUTrackerQueue::remove_expired_entries(double current_time) { double limit = current_time - _time_slice; while (_no_entries > 0) { if (is_double_geq(limit, _array[_tail_index].end_time())) { _tail_index = trim_index(_tail_index + 1); --_no_entries; } else return; } guarantee(_no_entries == 0, "should have no entries in the array"); } double G1MMUTrackerQueue::calculate_gc_time(double current_time) { double gc_time = 0.0; double limit = current_time - _time_slice; for (int i = 0; i < _no_entries; ++i) { int index = trim_index(_tail_index + i); G1MMUTrackerQueueElem *elem = &_array[index]; if (elem->end_time() > limit) { if (elem->start_time() > limit) gc_time += elem->duration(); else gc_time += elem->end_time() - limit; } } return gc_time; } void G1MMUTrackerQueue::add_pause(double start, double end, bool gc_thread) { double longest_allowed = longest_pause_internal(start); if (longest_allowed < 0.0) longest_allowed = 0.0; double duration = end - start; remove_expired_entries(end); if (_no_entries == QueueLength) { // OK, right now when we fill up we bomb out // there are a few ways of dealing with this "gracefully" // increase the array size (:-) // remove the oldest entry (this might allow more GC time for // the time slice than what's allowed) // concolidate the two entries with the minimum gap between them // (this mighte allow less GC time than what's allowed) guarantee(0, "array full, currently we can't recover"); } _head_index = trim_index(_head_index + 1); ++_no_entries; _array[_head_index] = G1MMUTrackerQueueElem(start, end); } // basically the _internal call does not remove expired entries // this is for trying things out in the future and a couple // of other places (debugging) double G1MMUTrackerQueue::longest_pause(double current_time) { if (_DISABLE_MMU) return _max_gc_time; MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); remove_expired_entries(current_time); return longest_pause_internal(current_time); } double G1MMUTrackerQueue::longest_pause_internal(double current_time) { double target_time = _max_gc_time; while( 1 ) { double gc_time = calculate_gc_time(current_time + target_time) + _conc_overhead_time_sec; double diff = target_time + gc_time - _max_gc_time; if (!is_double_leq_0(diff)) { target_time -= diff; if (is_double_leq_0(target_time)) { target_time = -1.0; break; } } else { break; } } return target_time; } // basically the _internal call does not remove expired entries // this is for trying things out in the future and a couple // of other places (debugging) double G1MMUTrackerQueue::when_sec(double current_time, double pause_time) { if (_DISABLE_MMU) return 0.0; MutexLockerEx x(MMUTracker_lock, Mutex::_no_safepoint_check_flag); remove_expired_entries(current_time); return when_internal(current_time, pause_time); } double G1MMUTrackerQueue::when_internal(double current_time, double pause_time) { // if the pause is over the maximum, just assume that it's the maximum double adjusted_pause_time = (pause_time > max_gc_time()) ? max_gc_time() : pause_time; double earliest_end = current_time + adjusted_pause_time; double limit = earliest_end - _time_slice; double gc_time = calculate_gc_time(earliest_end); double diff = gc_time + adjusted_pause_time - max_gc_time(); if (is_double_leq_0(diff)) return 0.0; int index = _tail_index; while ( 1 ) { G1MMUTrackerQueueElem *elem = &_array[index]; if (elem->end_time() > limit) { if (elem->start_time() > limit) diff -= elem->duration(); else diff -= elem->end_time() - limit; if (is_double_leq_0(diff)) return elem->end_time() + diff + _time_slice - adjusted_pause_time - current_time; } index = trim_index(index+1); guarantee(index != trim_index(_head_index + 1), "should not go past head"); } }