jdk-24/src/hotspot/share/gc/z/zMetronome.cpp
Per Lidén e7af7a4aef 8204210: Implementation: JEP 333: ZGC: A Scalable Low-Latency Garbage Collector (Experimental)
Co-authored-by: Stefan Karlsson <stefan.karlsson@oracle.com>
Co-authored-by: Erik Osterlund <erik.osterlund@oracle.com>
Co-authored-by: Mikael Gerdin <mikael.gerdin@oracle.com>
Co-authored-by: Kim Barrett <kim.barrett@oracle.com>
Co-authored-by: Nils Eliasson <nils.eliasson@oracle.com>
Co-authored-by: Rickard Backman <rickard.backman@oracle.com>
Co-authored-by: Roland Westrelin <rwestrel@redhat.com>
Co-authored-by: Coleen Phillimore <coleen.phillimore@oracle.com>
Co-authored-by: Robbin Ehn <robbin.ehn@oracle.com>
Co-authored-by: Gerard Ziemski <gerard.ziemski@oracle.com>
Co-authored-by: Hugh Wilkinson <hugh.wilkinson@intel.com>
Co-authored-by: Sandhya Viswanathan <sandhya.viswanathan@intel.com>
Co-authored-by: Bill Wheeler <bill.npo.wheeler@intel.com>
Co-authored-by: Vinay K. Awasthi <vinay.k.awasthi@intel.com>
Co-authored-by: Yasumasa Suenaga <yasuenag@gmail.com>
Reviewed-by: pliden, stefank, eosterlund, ehelin, sjohanss, rbackman, coleenp, ihse, jgeorge, lmesnik, rkennke
2018-06-12 17:40:28 +02:00

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/*
* Copyright (c) 2015, 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
#include "precompiled.hpp"
#include "gc/z/zMetronome.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/timer.hpp"
#include "utilities/ticks.hpp"
ZMetronome::ZMetronome(uint64_t hz) :
_monitor(Monitor::leaf, "ZMetronome", false, Monitor::_safepoint_check_never),
_interval_ms(MILLIUNITS / hz),
_start_ms(0),
_nticks(0),
_stopped(false) {}
uint64_t ZMetronome::nticks() const {
return _nticks;
}
bool ZMetronome::wait_for_tick() {
if (_nticks++ == 0) {
// First tick, set start time
const Ticks now = Ticks::now();
_start_ms = TimeHelper::counter_to_millis(now.value());
}
for (;;) {
// We might wake up spuriously from wait, so always recalculate
// the timeout after a wakeup to see if we need to wait again.
const Ticks now = Ticks::now();
const uint64_t now_ms = TimeHelper::counter_to_millis(now.value());
const uint64_t next_ms = _start_ms + (_interval_ms * _nticks);
const int64_t timeout_ms = next_ms - now_ms;
MonitorLockerEx ml(&_monitor, Monitor::_no_safepoint_check_flag);
if (!_stopped && timeout_ms > 0) {
// Wait
ml.wait(Monitor::_no_safepoint_check_flag, timeout_ms);
} else {
// Tick
return !_stopped;
}
}
}
void ZMetronome::stop() {
MonitorLockerEx ml(&_monitor, Monitor::_no_safepoint_check_flag);
_stopped = true;
ml.notify();
}