jdk8-mips64-public/hotspot: src/share/vm/utilities/taskqueue.cpp@5f429ee79634 (annotated)

src/share/vm/utilities/taskqueue.cpp@5f429ee79634 (annotated)

src/share/vm/utilities/taskqueue.cpp

Mon, 09 Aug 2010 05:41:05 -0700

author: jcoomes
date: Mon, 09 Aug 2010 05:41:05 -0700
changeset 2064: 5f429ee79634
parent 2020: a93a9eda13f7
child 2188: 8b10f48633dc
permissions: -rw-r--r--

6966222: G1: simplify TaskQueue overflow handling
Reviewed-by: tonyp, ysr

 /*
  * Copyright (c) 2001, 2010, 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 "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
 #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(_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;
   }
 }
 #ifdef ASSERT
 bool ObjArrayTask::is_valid() const {
   return _obj != NULL && _obj->is_objArray() && _index > 0 &&
     _index < objArrayOop(_obj)->length();
 }
 #endif // ASSERT

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/utilities/taskqueue.cpp@5f429ee79634 (annotated)

src/share/vm/utilities/taskqueue.cpp