lib/libkse/thread/thr_concurrency.c

   1 /*
   2  * Copyright (c) 2003 Daniel M. Eischen <deischen@freebsd.org>
   3  * Copyright (c) 2003 Sergey Osokin <osa@freebsd.org.ru>.
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Neither the name of the author nor the names of any co-contributors
  12  *    may be used to endorse or promote products derived from this software
  13  *    without specific prior written permission.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  *
  27  * $FreeBSD$
  28  */
  29 #include <errno.h>
  30 #include <pthread.h>
  31 #include <sys/types.h>
  32 #include <sys/sysctl.h>
  33
  34 #include "thr_private.h"
  35
  36 LT10_COMPAT_PRIVATE(_pthread_getconcurrency);
  37 LT10_COMPAT_DEFAULT(pthread_getconcurrency);
  38 LT10_COMPAT_PRIVATE(_pthread_setconcurrency);
  39 LT10_COMPAT_DEFAULT(pthread_setconcurrency);
  40
  41 /*#define DEBUG_CONCURRENCY */
  42 #ifdef DEBUG_CONCURRENCY
  43 #define DBG_MSG         stdout_debug
  44 #else
  45 #define DBG_MSG(x...)
  46 #endif
  47
  48 static int level = 0;
  49
  50 __weak_reference(_pthread_getconcurrency, pthread_getconcurrency);
  51 __weak_reference(_pthread_setconcurrency, pthread_setconcurrency);
  52
  53 int
  54 _pthread_getconcurrency(void)
  55 {
  56         return (level);
  57 }
  58
  59 int
  60 _pthread_setconcurrency(int new_level)
  61 {
  62         int ret;
  63
  64         if (new_level < 0)
  65                 ret = EINVAL;
  66         else if (new_level == level)
  67                 ret = 0;
  68         else if (new_level == 0) {
  69                 level = 0;
  70                 ret = 0;
  71         } else if ((_kse_isthreaded() == 0) && (_kse_setthreaded(1) != 0)) {
  72                 DBG_MSG("Can't enable threading.\n");
  73                 ret = EAGAIN;
  74         } else {
  75                 ret = _thr_setconcurrency(new_level);
  76                 if (ret == 0)
  77                         level = new_level;
  78         }
  79         return (ret);
  80 }
  81
  82 int
  83 _thr_setconcurrency(int new_level)
  84 {
  85         struct pthread *curthread;
  86         struct kse *newkse, *kse;
  87         kse_critical_t crit;
  88         int kse_count;
  89         int i;
  90         int ret;
  91
  92         /*
  93          * Turn on threaded mode, if failed, it is unnecessary to
  94          * do further work.
  95          */
  96         if (_kse_isthreaded() == 0 && _kse_setthreaded(1))
  97                 return (EAGAIN);
  98
  99         ret = 0;
 100         curthread = _get_curthread();
 101         /* Race condition, but so what. */
 102         kse_count = _kse_initial->k_kseg->kg_ksecount;
 103         if (new_level > kse_count) {
 104                 for (i = kse_count; i < new_level; i++) {
 105                         newkse = _kse_alloc(curthread, 0);
 106                         if (newkse == NULL) {
 107                                 DBG_MSG("Can't alloc new KSE.\n");
 108                                 ret = EAGAIN;
 109                                 break;
 110                         }
 111                         newkse->k_kseg = _kse_initial->k_kseg;
 112                         newkse->k_schedq = _kse_initial->k_schedq;
 113                         newkse->k_curthread = NULL;
 114                         crit = _kse_critical_enter();
 115                         KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
 116                         TAILQ_INSERT_TAIL(&newkse->k_kseg->kg_kseq,
 117                             newkse, k_kgqe);
 118                         newkse->k_kseg->kg_ksecount++;
 119                         newkse->k_flags |= KF_STARTED;
 120                         KSE_SCHED_UNLOCK(curthread->kse, newkse->k_kseg);
 121                         if (kse_create(&newkse->k_kcb->kcb_kmbx, 0) != 0) {
 122                                 KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
 123                                 TAILQ_REMOVE(&newkse->k_kseg->kg_kseq,
 124                                     newkse, k_kgqe);
 125                                 newkse->k_kseg->kg_ksecount--;
 126                                 KSE_SCHED_UNLOCK(curthread->kse,
 127                                     newkse->k_kseg);
 128                                 _kse_critical_leave(crit);
 129                                 _kse_free(curthread, newkse);
 130                                 DBG_MSG("kse_create syscall failed.\n");
 131                                 ret = EAGAIN;
 132                                 break;
 133                         } else {
 134                                 _kse_critical_leave(crit);
 135                         }
 136                 }
 137         } else if (new_level < kse_count) {
 138                 kse_count = 0;
 139                 crit = _kse_critical_enter();
 140                 KSE_SCHED_LOCK(curthread->kse, _kse_initial->k_kseg);
 141                 /* Count the number of active KSEs */
 142                 TAILQ_FOREACH(kse, &_kse_initial->k_kseg->kg_kseq, k_kgqe) {
 143                         if ((kse->k_flags & KF_TERMINATED) == 0)
 144                                 kse_count++;
 145                 }
 146                 /* Reduce the number of active KSEs appropriately. */
 147                 kse = TAILQ_FIRST(&_kse_initial->k_kseg->kg_kseq);
 148                 while ((kse != NULL) && (kse_count > new_level)) {
 149                         if ((kse != _kse_initial) &&
 150                             ((kse->k_flags & KF_TERMINATED) == 0)) {
 151                                 kse->k_flags |= KF_TERMINATED;
 152                                 kse_count--;
 153                                 /* Wakup the KSE in case it is idle. */
 154                                 kse_wakeup(&kse->k_kcb->kcb_kmbx);
 155                         }
 156                         kse = TAILQ_NEXT(kse, k_kgqe);
 157                 }
 158                 KSE_SCHED_UNLOCK(curthread->kse, _kse_initial->k_kseg);
 159                 _kse_critical_leave(crit);
 160         }
 161         return (ret);
 162 }
 163
 164 int
 165 _thr_setmaxconcurrency(void)
 166 {
 167         int vcpu;
 168         size_t len;
 169         int ret;
 170
 171         len = sizeof(vcpu);
 172         ret = sysctlbyname("kern.threads.virtual_cpu", &vcpu, &len, NULL, 0);
 173         if (ret == 0 && vcpu > 0)
 174                 ret = _thr_setconcurrency(vcpu);
 175         return (ret);
 176 }
 177