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/*
* Copyright (c) 2018, 2019, Red Hat, 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHPACER_HPP
#define SHARE_GC_SHENANDOAH_SHENANDOAHPACER_HPP
#include "gc/shenandoah/shenandoahNumberSeq.hpp"
#include "gc/shenandoah/shenandoahPadding.hpp"
#include "memory/allocation.hpp"
class ShenandoahHeap;
#define PACING_PROGRESS_UNINIT (-1)
#define PACING_PROGRESS_ZERO ( 0)
/**
* ShenandoahPacer provides allocation pacing mechanism.
*
* Currently it implements simple tax-and-spend pacing policy: GC threads provide
* credit, allocating thread spend the credit, or stall when credit is not available.
*/
class ShenandoahPacer : public CHeapObj<mtGC> {
private:
ShenandoahHeap* _heap;
double _last_time;
TruncatedSeq* _progress_history;
Monitor* _wait_monitor;
ShenandoahSharedFlag _need_notify_waiters;
// Set once per phase
volatile intptr_t _epoch;
volatile double _tax_rate;
// Heavily updated, protect from accidental false sharing
shenandoah_padding(0);
volatile intptr_t _budget;
shenandoah_padding(1);
// Heavily updated, protect from accidental false sharing
shenandoah_padding(2);
volatile intptr_t _progress;
shenandoah_padding(3);
public:
ShenandoahPacer(ShenandoahHeap* heap) :
_heap(heap),
_last_time(os::elapsedTime()),
_progress_history(new TruncatedSeq(5)),
_wait_monitor(new Monitor(Mutex::safepoint-1, "ShenandoahWaitMonitor_lock", true)),
_epoch(0),
_tax_rate(1),
_budget(0),
_progress(PACING_PROGRESS_UNINIT) {}
void setup_for_idle();
void setup_for_mark();
void setup_for_evac();
void setup_for_updaterefs();
void setup_for_reset();
inline void report_mark(size_t words);
inline void report_evac(size_t words);
inline void report_updaterefs(size_t words);
inline void report_alloc(size_t words);
bool claim_for_alloc(size_t words, bool force);
void pace_for_alloc(size_t words);
void unpace_for_alloc(intptr_t epoch, size_t words);
void notify_waiters();
intptr_t epoch();
void flush_stats_to_cycle();
void print_cycle_on(outputStream* out);
private:
inline void report_internal(size_t words);
inline void report_progress_internal(size_t words);
inline void add_budget(size_t words);
void restart_with(size_t non_taxable_bytes, double tax_rate);
size_t update_and_get_progress_history();
void wait(size_t time_ms);
};
#endif // SHARE_GC_SHENANDOAH_SHENANDOAHPACER_HPP
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