taskqueue.cpp revision 470
0N/A/*
0N/A * Copyright 2001-2008 Sun Microsystems, Inc. All Rights Reserved.
0N/A * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
0N/A *
0N/A * This code is free software; you can redistribute it and/or modify it
0N/A * under the terms of the GNU General Public License version 2 only, as
0N/A * published by the Free Software Foundation.
0N/A *
0N/A * This code is distributed in the hope that it will be useful, but WITHOUT
0N/A * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
0N/A * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
0N/A * version 2 for more details (a copy is included in the LICENSE file that
0N/A * accompanied this code).
0N/A *
0N/A * You should have received a copy of the GNU General Public License version
0N/A * 2 along with this work; if not, write to the Free Software Foundation,
0N/A * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
0N/A *
0N/A * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
0N/A * CA 95054 USA or visit www.sun.com if you need additional information or
0N/A * have any questions.
0N/A *
0N/A */
0N/A
0N/A# include "incls/_precompiled.incl"
0N/A# include "incls/_taskqueue.cpp.incl"
0N/A
0N/Abool TaskQueueSuper::peek() {
0N/A return _bottom != _age.top();
0N/A}
0N/A
0N/Aint TaskQueueSetSuper::randomParkAndMiller(int *seed0) {
0N/A const int a = 16807;
0N/A const int m = 2147483647;
0N/A const int q = 127773; /* m div a */
0N/A const int r = 2836; /* m mod a */
0N/A assert(sizeof(int) == 4, "I think this relies on that");
0N/A int seed = *seed0;
0N/A int hi = seed / q;
0N/A int lo = seed % q;
0N/A int test = a * lo - r * hi;
0N/A if (test > 0)
seed = test;
else
seed = test + m;
*seed0 = seed;
return seed;
}
ParallelTaskTerminator::
ParallelTaskTerminator(int n_threads, TaskQueueSetSuper* queue_set) :
_n_threads(n_threads),
_queue_set(queue_set),
_offered_termination(0) {}
bool ParallelTaskTerminator::peek_in_queue_set() {
return _queue_set->peek();
}
void ParallelTaskTerminator::yield() {
os::yield();
}
void ParallelTaskTerminator::sleep(uint millis) {
os::sleep(Thread::current(), millis, false);
}
bool
ParallelTaskTerminator::offer_termination(TerminatorTerminator* terminator) {
Atomic::inc(&_offered_termination);
juint yield_count = 0;
while (true) {
if (_offered_termination == _n_threads) {
//inner_termination_loop();
return true;
} else {
if (yield_count <= WorkStealingYieldsBeforeSleep) {
yield_count++;
yield();
} else {
if (PrintGCDetails && Verbose) {
gclog_or_tty->print_cr("ParallelTaskTerminator::offer_termination() "
"thread %d sleeps after %d yields",
Thread::current(), yield_count);
}
yield_count = 0;
// A sleep will cause this processor to seek work on another processor's
// runqueue, if it has nothing else to run (as opposed to the yield
// which may only move the thread to the end of the this processor's
// runqueue).
sleep(WorkStealingSleepMillis);
}
if (peek_in_queue_set() ||
(terminator != NULL && terminator->should_exit_termination())) {
Atomic::dec(&_offered_termination);
return false;
}
}
}
}
void ParallelTaskTerminator::reset_for_reuse() {
if (_offered_termination != 0) {
assert(_offered_termination == _n_threads,
"Terminator may still be in use");
_offered_termination = 0;
}
}
bool RegionTaskQueueWithOverflow::is_empty() {
return (_region_queue.size() == 0) &&
(_overflow_stack->length() == 0);
}
bool RegionTaskQueueWithOverflow::stealable_is_empty() {
return _region_queue.size() == 0;
}
bool RegionTaskQueueWithOverflow::overflow_is_empty() {
return _overflow_stack->length() == 0;
}
void RegionTaskQueueWithOverflow::initialize() {
_region_queue.initialize();
assert(_overflow_stack == 0, "Creating memory leak");
_overflow_stack =
new (ResourceObj::C_HEAP) GrowableArray<RegionTask>(10, true);
}
void RegionTaskQueueWithOverflow::save(RegionTask t) {
if (TraceRegionTasksQueuing && Verbose) {
gclog_or_tty->print_cr("CTQ: save " PTR_FORMAT, t);
}
if(!_region_queue.push(t)) {
_overflow_stack->push(t);
}
}
// Note that using this method will retrieve all regions
// that have been saved but that it will always check
// the overflow stack. It may be more efficient to
// check the stealable queue and the overflow stack
// separately.
bool RegionTaskQueueWithOverflow::retrieve(RegionTask& region_task) {
bool result = retrieve_from_overflow(region_task);
if (!result) {
result = retrieve_from_stealable_queue(region_task);
}
if (TraceRegionTasksQueuing && Verbose && result) {
gclog_or_tty->print_cr(" CTQ: retrieve " PTR_FORMAT, result);
}
return result;
}
bool RegionTaskQueueWithOverflow::retrieve_from_stealable_queue(
RegionTask& region_task) {
bool result = _region_queue.pop_local(region_task);
if (TraceRegionTasksQueuing && Verbose) {
gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
}
return result;
}
bool
RegionTaskQueueWithOverflow::retrieve_from_overflow(RegionTask& region_task) {
bool result;
if (!_overflow_stack->is_empty()) {
region_task = _overflow_stack->pop();
result = true;
} else {
region_task = (RegionTask) NULL;
result = false;
}
if (TraceRegionTasksQueuing && Verbose) {
gclog_or_tty->print_cr("CTQ: retrieve_stealable " PTR_FORMAT, region_task);
}
return result;
}