Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2001, 2014, 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 "oops/oop.inline.hpp"

 #include "runtime/os.hpp"

 #include "runtime/thread.inline.hpp"

 #include "utilities/debug.hpp"

 #include "utilities/stack.inline.hpp"

 #include "utilities/taskqueue.hpp"

 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

 #ifdef TRACESPINNING

 uint ParallelTaskTerminator::_total_yields = 0;

 uint ParallelTaskTerminator::_total_spins = 0;

 uint ParallelTaskTerminator::_total_peeks = 0;

 #endif

 #if TASKQUEUE_STATS

 const char * const TaskQueueStats::_names[last_stat_id] = {

   "qpush", "qpop", "qpop-s", "qattempt", "qsteal", "opush", "omax"

 };

 TaskQueueStats & TaskQueueStats::operator +=(const TaskQueueStats & addend)

 {

   for (unsigned int i = 0; i < last_stat_id; ++i) {

     _stats[i] += addend._stats[i];

   }

   return *this;

 }

 void TaskQueueStats::print_header(unsigned int line, outputStream* const stream,

                                   unsigned int width)

 {

   // Use a width w: 1 <= w <= max_width

   const unsigned int max_width = 40;

   const unsigned int w = MAX2(MIN2(width, max_width), 1U);

   if (line == 0) { // spaces equal in width to the header

     const unsigned int hdr_width = w * last_stat_id + last_stat_id - 1;

     stream->print("%*s", hdr_width, " ");

   } else if (line == 1) { // labels

     stream->print("%*s", w, _names[0]);

     for (unsigned int i = 1; i < last_stat_id; ++i) {

       stream->print(" %*s", w, _names[i]);

     }

   } else if (line == 2) { // dashed lines

     char dashes[max_width + 1];

     memset(dashes, '-', w);

     dashes[w] = '\0';

     stream->print("%s", dashes);

     for (unsigned int i = 1; i < last_stat_id; ++i) {

       stream->print(" %s", dashes);

     }

   }

 }

 void TaskQueueStats::print(outputStream* stream, unsigned int width) const

 {

   #define FMT SIZE_FORMAT_W(*)

   stream->print(FMT, width, _stats[0]);

   for (unsigned int i = 1; i < last_stat_id; ++i) {

     stream->print(" " FMT, width, _stats[i]);

   }

   #undef FMT

 }

 #ifdef ASSERT

 // Invariants which should hold after a TaskQueue has been emptied and is

 // quiescent; they do not hold at arbitrary times.

 void TaskQueueStats::verify() const

 {

   assert(get(push) == get(pop) + get(steal),

          err_msg("push=" SIZE_FORMAT " pop=" SIZE_FORMAT " steal=" SIZE_FORMAT,

                  get(push), get(pop), get(steal)));

   assert(get(pop_slow) <= get(pop),

          err_msg("pop_slow=" SIZE_FORMAT " pop=" SIZE_FORMAT,

                  get(pop_slow), get(pop)));

   assert(get(steal) <= get(steal_attempt),

          err_msg("steal=" SIZE_FORMAT " steal_attempt=" SIZE_FORMAT,

                  get(steal), get(steal_attempt)));

   assert(get(overflow) == 0 || get(push) != 0,

          err_msg("overflow=" SIZE_FORMAT " push=" SIZE_FORMAT,

                  get(overflow), get(push)));

   assert(get(overflow_max_len) == 0 || get(overflow) != 0,

          err_msg("overflow_max_len=" SIZE_FORMAT " overflow=" SIZE_FORMAT,

                  get(overflow_max_len), get(overflow)));

 }

 #endif // ASSERT

 #endif // TASKQUEUE_STATS

 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(_n_threads > 0, "Initialization is incorrect");

   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: " UINT32_FORMAT

     " Total spins: " UINT32_FORMAT " Total peeks: " UINT32_FORMAT,

     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;

   }

 }

 #ifdef ASSERT

 bool ObjArrayTask::is_valid() const {

   return _obj != NULL && _obj->is_objArray() && _index > 0 &&

     _index < objArrayOop(_obj)->length();

 }

 #endif // ASSERT

 void ParallelTaskTerminator::reset_for_reuse(int n_threads) {

   reset_for_reuse();

   _n_threads = n_threads;

 }