| /* |
| * Copyright 2001-2009 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/_taskqueue.cpp.incl" |
| |
| #ifdef TRACESPINNING |
| uint ParallelTaskTerminator::_total_yields = 0; |
| uint ParallelTaskTerminator::_total_spins = 0; |
| uint ParallelTaskTerminator::_total_peeks = 0; |
| #endif |
| |
| bool TaskQueueSuper::peek() { |
| return _bottom != _age.top(); |
| } |
| |
| int TaskQueueSetSuper::randomParkAndMiller(int *seed0) { |
| const int a = 16807; |
| const int m = 2147483647; |
| const int q = 127773; /* m div a */ |
| const int r = 2836; /* m mod a */ |
| assert(sizeof(int) == 4, "I think this relies on that"); |
| int seed = *seed0; |
| int hi = seed / q; |
| int lo = seed % q; |
| int test = a * lo - r * hi; |
| 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() { |
| assert(_offered_termination <= _n_threads, "Invariant"); |
| os::yield(); |
| } |
| |
| void ParallelTaskTerminator::sleep(uint millis) { |
| assert(_offered_termination <= _n_threads, "Invariant"); |
| os::sleep(Thread::current(), millis, false); |
| } |
| |
| bool |
| ParallelTaskTerminator::offer_termination(TerminatorTerminator* terminator) { |
| assert(_offered_termination < _n_threads, "Invariant"); |
| Atomic::inc(&_offered_termination); |
| |
| uint yield_count = 0; |
| // Number of hard spin loops done since last yield |
| uint hard_spin_count = 0; |
| // Number of iterations in the hard spin loop. |
| uint hard_spin_limit = WorkStealingHardSpins; |
| |
| // If WorkStealingSpinToYieldRatio is 0, no hard spinning is done. |
| // If it is greater than 0, then start with a small number |
| // of spins and increase number with each turn at spinning until |
| // the count of hard spins exceeds WorkStealingSpinToYieldRatio. |
| // Then do a yield() call and start spinning afresh. |
| if (WorkStealingSpinToYieldRatio > 0) { |
| hard_spin_limit = WorkStealingHardSpins >> WorkStealingSpinToYieldRatio; |
| hard_spin_limit = MAX2(hard_spin_limit, 1U); |
| } |
| // Remember the initial spin limit. |
| uint hard_spin_start = hard_spin_limit; |
| |
| // Loop waiting for all threads to offer termination or |
| // more work. |
| while (true) { |
| assert(_offered_termination <= _n_threads, "Invariant"); |
| // Are all threads offering termination? |
| if (_offered_termination == _n_threads) { |
| return true; |
| } else { |
| // Look for more work. |
| // Periodically sleep() instead of yield() to give threads |
| // waiting on the cores the chance to grab this code |
| if (yield_count <= WorkStealingYieldsBeforeSleep) { |
| // Do a yield or hardspin. For purposes of deciding whether |
| // to sleep, count this as a yield. |
| yield_count++; |
| |
| // Periodically call yield() instead spinning |
| // After WorkStealingSpinToYieldRatio spins, do a yield() call |
| // and reset the counts and starting limit. |
| if (hard_spin_count > WorkStealingSpinToYieldRatio) { |
| yield(); |
| hard_spin_count = 0; |
| hard_spin_limit = hard_spin_start; |
| #ifdef TRACESPINNING |
| _total_yields++; |
| #endif |
| } else { |
| // Hard spin this time |
| // Increase the hard spinning period but only up to a limit. |
| hard_spin_limit = MIN2(2*hard_spin_limit, |
| (uint) WorkStealingHardSpins); |
| for (uint j = 0; j < hard_spin_limit; j++) { |
| SpinPause(); |
| } |
| hard_spin_count++; |
| #ifdef TRACESPINNING |
| _total_spins++; |
| #endif |
| } |
| } 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); |
| } |
| |
| #ifdef TRACESPINNING |
| _total_peeks++; |
| #endif |
| if (peek_in_queue_set() || |
| (terminator != NULL && terminator->should_exit_termination())) { |
| Atomic::dec(&_offered_termination); |
| assert(_offered_termination < _n_threads, "Invariant"); |
| return false; |
| } |
| } |
| } |
| } |
| |
| #ifdef TRACESPINNING |
| void ParallelTaskTerminator::print_termination_counts() { |
| gclog_or_tty->print_cr("ParallelTaskTerminator Total yields: %lld " |
| "Total spins: %lld Total peeks: %lld", |
| total_yields(), |
| total_spins(), |
| total_peeks()); |
| } |
| #endif |
| |
| 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; |
| } |