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src/share/vm/utilities/taskqueue.cpp@c96030fff130 (annotated)

src/share/vm/utilities/taskqueue.cpp

Thu, 20 Nov 2008 16:56:09 -0800

author

ysr

date

Thu, 20 Nov 2008 16:56:09 -0800

changeset 888

c96030fff130

parent 810

81cd571500b0

child 905

ad8c8ca4ab0f

permissions

-rw-r--r--

6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa

duke@435	1	/*
duke@435	2	* Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	# include "incls/_precompiled.incl"
duke@435	26	# include "incls/_taskqueue.cpp.incl"
duke@435	27
duke@435	28	bool TaskQueueSuper::peek() {
duke@435	29	return _bottom != _age.top();
duke@435	30	}
duke@435	31
duke@435	32	int TaskQueueSetSuper::randomParkAndMiller(int *seed0) {
duke@435	33	const int a = 16807;
duke@435	34	const int m = 2147483647;
duke@435	35	const int q = 127773; /* m div a */
duke@435	36	const int r = 2836; /* m mod a */
duke@435	37	assert(sizeof(int) == 4, "I think this relies on that");
duke@435	38	int seed = *seed0;
duke@435	39	int hi = seed / q;
duke@435	40	int lo = seed % q;
duke@435	41	int test = a * lo - r * hi;
duke@435	42	if (test > 0)
duke@435	43	seed = test;
duke@435	44	else
duke@435	45	seed = test + m;
duke@435	46	*seed0 = seed;
duke@435	47	return seed;
duke@435	48	}
duke@435	49
duke@435	50	ParallelTaskTerminator::
duke@435	51	ParallelTaskTerminator(int n_threads, TaskQueueSetSuper* queue_set) :
duke@435	52	_n_threads(n_threads),
duke@435	53	_queue_set(queue_set),
duke@435	54	_offered_termination(0) {}
duke@435	55
duke@435	56	bool ParallelTaskTerminator::peek_in_queue_set() {
duke@435	57	return _queue_set->peek();
duke@435	58	}
duke@435	59
duke@435	60	void ParallelTaskTerminator::yield() {
duke@435	61	os::yield();
duke@435	62	}
duke@435	63
duke@435	64	void ParallelTaskTerminator::sleep(uint millis) {
duke@435	65	os::sleep(Thread::current(), millis, false);
duke@435	66	}
duke@435	67
ysr@777	68	bool
ysr@777	69	ParallelTaskTerminator::offer_termination(TerminatorTerminator* terminator) {
duke@435	70	Atomic::inc(&_offered_termination);
duke@435	71
duke@435	72	juint yield_count = 0;
duke@435	73	while (true) {
duke@435	74	if (_offered_termination == _n_threads) {
duke@435	75	//inner_termination_loop();
duke@435	76	return true;
duke@435	77	} else {
duke@435	78	if (yield_count <= WorkStealingYieldsBeforeSleep) {
duke@435	79	yield_count++;
duke@435	80	yield();
duke@435	81	} else {
duke@435	82	if (PrintGCDetails && Verbose) {
duke@435	83	gclog_or_tty->print_cr("ParallelTaskTerminator::offer_termination() "
duke@435	84	"thread %d sleeps after %d yields",
duke@435	85	Thread::current(), yield_count);
duke@435	86	}
duke@435	87	yield_count = 0;
duke@435	88	// A sleep will cause this processor to seek work on another processor's
duke@435	89	// runqueue, if it has nothing else to run (as opposed to the yield
duke@435	90	// which may only move the thread to the end of the this processor's
duke@435	91	// runqueue).
duke@435	92	sleep(WorkStealingSleepMillis);
duke@435	93	}
duke@435	94
ysr@777	95	if (peek_in_queue_set() ||
ysr@777	96	(terminator != NULL && terminator->should_exit_termination())) {
duke@435	97	Atomic::dec(&_offered_termination);
duke@435	98	return false;
duke@435	99	}
duke@435	100	}
duke@435	101	}
duke@435	102	}
duke@435	103
duke@435	104	void ParallelTaskTerminator::reset_for_reuse() {
duke@435	105	if (_offered_termination != 0) {
duke@435	106	assert(_offered_termination == _n_threads,
duke@435	107	"Terminator may still be in use");
duke@435	108	_offered_termination = 0;
duke@435	109	}
duke@435	110	}
duke@435	111
jcoomes@810	112	bool RegionTaskQueueWithOverflow::is_empty() {
jcoomes@810	113	return (_region_queue.size() == 0) &&
duke@435	114	(_overflow_stack->length() == 0);
duke@435	115	}
duke@435	116
jcoomes@810	117	bool RegionTaskQueueWithOverflow::stealable_is_empty() {
jcoomes@810	118	return _region_queue.size() == 0;
duke@435	119	}
duke@435	120
jcoomes@810	121	bool RegionTaskQueueWithOverflow::overflow_is_empty() {
duke@435	122	return _overflow_stack->length() == 0;
duke@435	123	}
duke@435	124
jcoomes@810	125	void RegionTaskQueueWithOverflow::initialize() {
jcoomes@810	126	_region_queue.initialize();
duke@435	127	assert(_overflow_stack == 0, "Creating memory leak");
duke@435	128	_overflow_stack =
jcoomes@810	129	new (ResourceObj::C_HEAP) GrowableArray<RegionTask>(10, true);
duke@435	130	}
duke@435	131
jcoomes@810	132	void RegionTaskQueueWithOverflow::save(RegionTask t) {
jcoomes@810	133	if (TraceRegionTasksQueuing && Verbose) {
duke@435	134	gclog_or_tty->print_cr("CTQ: save " PTR_FORMAT, t);
duke@435	135	}
jcoomes@810	136	if(!_region_queue.push(t)) {
duke@435	137	_overflow_stack->push(t);
duke@435	138	}
duke@435	139	}
duke@435	140
jcoomes@810	141	// Note that using this method will retrieve all regions
duke@435	142	// that have been saved but that it will always check
duke@435	143	// the overflow stack. It may be more efficient to
duke@435	144	// check the stealable queue and the overflow stack
duke@435	145	// separately.
jcoomes@810	146	bool RegionTaskQueueWithOverflow::retrieve(RegionTask& region_task) {
jcoomes@810	147	bool result = retrieve_from_overflow(region_task);
duke@435	148	if (!result) {
jcoomes@810	149	result = retrieve_from_stealable_queue(region_task);
duke@435	150	}
jcoomes@810	151	if (TraceRegionTasksQueuing && Verbose && result) {
duke@435	152	gclog_or_tty->print_cr(" CTQ: retrieve " PTR_FORMAT, result);
duke@435	153	}
duke@435	154	return result;
duke@435	155	}
duke@435	156
jcoomes@810	157	bool RegionTaskQueueWithOverflow::retrieve_from_stealable_queue(
jcoomes@810	158	RegionTask& region_task) {
jcoomes@810	159	bool result = _region_queue.pop_local(region_task);
jcoomes@810	160	if (TraceRegionTasksQueuing && Verbose) {
jcoomes@810	161	gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
duke@435	162	}
duke@435	163	return result;
duke@435	164	}
duke@435	165
jcoomes@810	166	bool
jcoomes@810	167	RegionTaskQueueWithOverflow::retrieve_from_overflow(RegionTask& region_task) {
duke@435	168	bool result;
duke@435	169	if (!_overflow_stack->is_empty()) {
jcoomes@810	170	region_task = _overflow_stack->pop();
duke@435	171	result = true;
duke@435	172	} else {
jcoomes@810	173	region_task = (RegionTask) NULL;
duke@435	174	result = false;
duke@435	175	}
jcoomes@810	176	if (TraceRegionTasksQueuing && Verbose) {
jcoomes@810	177	gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
duke@435	178	}
duke@435	179	return result;
duke@435	180	}