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
  30 #include "namespace.h"
  31 #include <errno.h>
  32 #include <pthread.h>
  33 #include <sys/types.h>
  34 #include <sys/sysctl.h>
  35 #include "un-namespace.h"
  36
  37 #include "thr_private.h"
  38
  39 /*#define DEBUG_CONCURRENCY */
  40 #ifdef DEBUG_CONCURRENCY
  41 #define DBG_MSG         stdout_debug
  42 #else
  43 #define DBG_MSG(x...)
  44 #endif
  45
  46 static int level = 0;
  47
  48 __weak_reference(_pthread_getconcurrency, pthread_getconcurrency);
  49 __weak_reference(_pthread_setconcurrency, pthread_setconcurrency);
  50
  51 int
  52 _pthread_getconcurrency(void)
  53 {
  54         return (level);
  55 }
  56
  57 int
  58 _pthread_setconcurrency(int new_level)
  59 {
  60         int ret;
  61
  62         if (new_level < 0)
  63                 ret = EINVAL;
  64         else if (new_level == level)
  65                 ret = 0;
  66         else if (new_level == 0) {
  67                 level = 0;
  68                 ret = 0;
  69         } else if ((_kse_isthreaded() == 0) && (_kse_setthreaded(1) != 0)) {
  70                 DBG_MSG("Can't enable threading.\n");
  71                 ret = EAGAIN;
  72         } else {
  73                 ret = _thr_setconcurrency(new_level);
  74                 if (ret == 0)
  75                         level = new_level;
  76         }
  77         return (ret);
  78 }
  79
  80 int
  81 _thr_setconcurrency(int new_level)
  82 {
  83         struct pthread *curthread;
  84         struct kse *newkse, *kse;
  85         kse_critical_t crit;
  86         int kse_count;
  87         int i;
  88         int ret;
  89
  90         /*
  91          * Turn on threaded mode, if failed, it is unnecessary to
  92          * do further work.
  93          */
  94         if (_kse_isthreaded() == 0 && _kse_setthreaded(1))
  95                 return (EAGAIN);
  96
  97         ret = 0;
  98         curthread = _get_curthread();
  99         /* Race condition, but so what. */
 100         kse_count = _kse_initial->k_kseg->kg_ksecount;
 101         if (new_level > kse_count) {
 102                 for (i = kse_count; i < new_level; i++) {
 103                         newkse = _kse_alloc(curthread, 0);
 104                         if (newkse == NULL) {
 105                                 DBG_MSG("Can't alloc new KSE.\n");
 106                                 ret = EAGAIN;
 107                                 break;
 108                         }
 109                         newkse->k_kseg = _kse_initial->k_kseg;
 110                         newkse->k_schedq = _kse_initial->k_schedq;
 111                         newkse->k_curthread = NULL;
 112                         crit = _kse_critical_enter();
 113                         KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
 114                         TAILQ_INSERT_TAIL(&newkse->k_kseg->kg_kseq,
 115                             newkse, k_kgqe);
 116                         newkse->k_kseg->kg_ksecount++;
 117                         newkse->k_flags |= KF_STARTED;
 118                         KSE_SCHED_UNLOCK(curthread->kse, newkse->k_kseg);
 119                         if (kse_create(&newkse->k_kcb->kcb_kmbx, 0) != 0) {
 120                                 KSE_SCHED_LOCK(curthread->kse, newkse->k_kseg);
 121                                 TAILQ_REMOVE(&newkse->k_kseg->kg_kseq,
 122                                     newkse, k_kgqe);
 123                                 newkse->k_kseg->kg_ksecount--;
 124                                 KSE_SCHED_UNLOCK(curthread->kse,
 125                                     newkse->k_kseg);
 126                                 _kse_critical_leave(crit);
 127                                 _kse_free(curthread, newkse);
 128                                 DBG_MSG("kse_create syscall failed.\n");
 129                                 ret = EAGAIN;
 130                                 break;
 131                         } else {
 132                                 _kse_critical_leave(crit);
 133                         }
 134                 }
 135         } else if (new_level < kse_count) {
 136                 kse_count = 0;
 137                 crit = _kse_critical_enter();
 138                 KSE_SCHED_LOCK(curthread->kse, _kse_initial->k_kseg);
 139                 /* Count the number of active KSEs */
 140                 TAILQ_FOREACH(kse, &_kse_initial->k_kseg->kg_kseq, k_kgqe) {
 141                         if ((kse->k_flags & KF_TERMINATED) == 0)
 142                                 kse_count++;
 143                 }
 144                 /* Reduce the number of active KSEs appropriately. */
 145                 kse = TAILQ_FIRST(&_kse_initial->k_kseg->kg_kseq);
 146                 while ((kse != NULL) && (kse_count > new_level)) {
 147                         if ((kse != _kse_initial) &&
 148                             ((kse->k_flags & KF_TERMINATED) == 0)) {
 149                                 kse->k_flags |= KF_TERMINATED;
 150                                 kse_count--;
 151                                 /* Wakup the KSE in case it is idle. */
 152                                 kse_wakeup(&kse->k_kcb->kcb_kmbx);
 153                         }
 154                         kse = TAILQ_NEXT(kse, k_kgqe);
 155                 }
 156                 KSE_SCHED_UNLOCK(curthread->kse, _kse_initial->k_kseg);
 157                 _kse_critical_leave(crit);
 158         }
 159         return (ret);
 160 }
 161
 162 int
 163 _thr_setmaxconcurrency(void)
 164 {
 165         int vcpu;
 166         size_t len;
 167         int ret;
 168
 169         len = sizeof(vcpu);
 170         ret = sysctlbyname("kern.threads.virtual_cpu", &vcpu, &len, NULL, 0);
 171         if (ret == 0 && vcpu > 0)
 172                 ret = _thr_setconcurrency(vcpu);
 173         return (ret);
 174 }
 175