sys/kern/kern_usched.c

   1 /*
   2  * Copyright (c) 2005 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Sergey Glushchenko <deen@smz.com.ua>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/kern/kern_usched.c,v 1.9 2007/07/02 17:06:55 dillon Exp $
  35  */
  36
  37 #include <sys/errno.h>
  38 #include <sys/globaldata.h>             /* curthread */
  39 #include <sys/proc.h>
  40 #include <sys/priv.h>
  41 #include <sys/sysproto.h>               /* struct usched_set_args */
  42 #include <sys/systm.h>                  /* strcmp() */
  43 #include <sys/usched.h>
  44 #include <machine/smp.h>
  45
  46 static TAILQ_HEAD(, usched) usched_list = TAILQ_HEAD_INITIALIZER(usched_list);
  47
  48 cpumask_t usched_mastermask = -1;
  49
  50 /*
  51  * Called from very low level boot code, i386/i386/machdep.c/init386().
  52  * We cannot do anything fancy.  no malloc's, no nothing other then
  53  * static initialization.
  54  */
  55 struct usched *
  56 usched_init(void)
  57 {
  58         const char *defsched;
  59
  60         defsched = kgetenv("kern.user_scheduler");
  61
  62         /*
  63          * Add various userland schedulers to the system.
  64          */
  65         usched_ctl(&usched_bsd4, USCH_ADD);
  66         usched_ctl(&usched_dummy, USCH_ADD);
  67         if (defsched == NULL )
  68                 return(&usched_bsd4);
  69         if (strcmp(defsched, "bsd4") == 0)
  70                 return(&usched_bsd4);
  71         kprintf("WARNING: Running dummy userland scheduler\n");
  72         return(&usched_dummy);
  73 }
  74
  75 /*
  76  * USCHED_CTL
  77  *
  78  * SYNOPSIS:
  79  *      Add/remove usched to/from list.
  80  *
  81  * ARGUMENTS:
  82  *      usched - pointer to target scheduler
  83  *      action - addition or removal ?
  84  *
  85  * RETURN VALUES:
  86  *      0 - success
  87  *      EINVAL - error
  88  */
  89 int
  90 usched_ctl(struct usched *usched, int action)
  91 {
  92         struct usched *item;    /* temporaly for TAILQ processing */
  93         int error = 0;
  94
  95         switch(action) {
  96         case USCH_ADD:
  97                 /*
  98                  * Make sure it isn't already on the list
  99                  */
 100 #ifdef INVARIANTS
 101                 TAILQ_FOREACH(item, &usched_list, entry) {
 102                         KKASSERT(item != usched);
 103                 }
 104 #endif
 105                 /*
 106                  * Optional callback to the scheduler before we officially
 107                  * add it to the list.
 108                  */
 109                 if (usched->usched_register)
 110                         usched->usched_register();
 111                 TAILQ_INSERT_TAIL(&usched_list, usched, entry);
 112                 break;
 113         case USCH_REM:
 114                 /*
 115                  * Do not allow the default scheduler to be removed
 116                  */
 117                 if (strcmp(usched->name, "bsd4") == 0) {
 118                         error = EINVAL;
 119                         break;
 120                 }
 121                 TAILQ_FOREACH(item, &usched_list, entry) {
 122                         if (item == usched)
 123                                 break;
 124                 }
 125                 if (item) {
 126                         if (item->usched_unregister)
 127                                 item->usched_unregister();
 128                         TAILQ_REMOVE(&usched_list, item, entry);
 129                 } else {
 130                         error = EINVAL;
 131                 }
 132                 break;
 133         default:
 134                 error = EINVAL;
 135                 break;
 136         }
 137         return (error);
 138 }
 139
 140 /*
 141  * USCHED_SET(syscall)
 142  *
 143  * SYNOPSIS:
 144  *      Setting up a proc's usched.
 145  *
 146  * ARGUMENTS:
 147  *      pid     -
 148  *      cmd     -
 149  *      data    -
 150  *      bytes   -
 151  * RETURN VALUES:
 152  *      0 - success
 153  *      EINVAL - error
 154  */
 155 int
 156 sys_usched_set(struct usched_set_args *uap)
 157 {
 158         struct proc *p = curthread->td_proc;
 159         struct usched *item;    /* temporaly for TAILQ processing */
 160         int error;
 161         char buffer[NAME_LENGTH];
 162         cpumask_t mask;
 163         struct lwp *lp;
 164         int cpuid;
 165
 166         if ((error = priv_check(curthread, PRIV_ROOT)) != 0)
 167                 return (error);
 168
 169         if (uap->pid != 0 && uap->pid != curthread->td_proc->p_pid)
 170                 return (EINVAL);
 171
 172         lp = curthread->td_lwp;
 173         switch (uap->cmd) {
 174         case USCHED_SET_SCHEDULER:
 175                 if ((error = copyinstr(uap->data, buffer, sizeof(buffer),
 176                         NULL)) != 0)
 177                         return (error);
 178                 TAILQ_FOREACH(item, &usched_list, entry) {
 179                         if ((strcmp(item->name, buffer) == 0))
 180                                 break;
 181                 }
 182
 183                 /*
 184                  * If the scheduler for a process is being changed, disassociate
 185                  * the old scheduler before switching to the new one.
 186                  *
 187                  * XXX we might have to add an additional ABI call to do a 'full
 188                  * disassociation' and another ABI call to do a 'full
 189                  * reassociation'
 190                  */
 191                 /* XXX lwp have to deal with multiple lwps here */
 192                 if (p->p_nthreads != 1)
 193                         return (EINVAL);
 194                 if (item && item != p->p_usched) {
 195                         /* XXX lwp */
 196                         p->p_usched->release_curproc(ONLY_LWP_IN_PROC(p));
 197                         p->p_usched = item;
 198                 } else if (item == NULL) {
 199                         error = EINVAL;
 200                 }
 201                 break;
 202         case USCHED_SET_CPU:
 203                 if (uap->bytes != sizeof(int))
 204                         return (EINVAL);
 205                 error = copyin(uap->data, &cpuid, sizeof(int));
 206                 if (error)
 207                         break;
 208                 if (cpuid < 0 || cpuid >= ncpus) {
 209                         error = EFBIG;
 210                         break;
 211                 }
 212                 if ((smp_active_mask & (1 << cpuid)) == 0) {
 213                         error = EINVAL;
 214                         break;
 215                 }
 216                 lp->lwp_cpumask = 1 << cpuid;
 217                 if (cpuid != mycpu->gd_cpuid)
 218                         lwkt_migratecpu(cpuid);
 219                 break;
 220         case USCHED_ADD_CPU:
 221                 if (uap->bytes != sizeof(int))
 222                         return (EINVAL);
 223                 error = copyin(uap->data, &cpuid, sizeof(int));
 224                 if (error)
 225                         break;
 226                 if (cpuid < 0 || cpuid >= ncpus) {
 227                         error = EFBIG;
 228                         break;
 229                 }
 230                 if (!(smp_active_mask & (1 << cpuid))) {
 231                         error = EINVAL;
 232                         break;
 233                 }
 234                 lp->lwp_cpumask |= 1 << cpuid;
 235                 break;
 236         case USCHED_DEL_CPU:
 237                 if (uap->bytes != sizeof(int))
 238                         return (EINVAL);
 239                 error = copyin(uap->data, &cpuid, sizeof(int));
 240                 if (error)
 241                         break;
 242                 if (cpuid < 0 || cpuid >= ncpus) {
 243                         error = EFBIG;
 244                         break;
 245                 }
 246                 lp = curthread->td_lwp;
 247                 mask = lp->lwp_cpumask & smp_active_mask & ~(1 << cpuid);
 248                 if (mask == 0)
 249                         error = EPERM;
 250                 else {
 251                         lp->lwp_cpumask &= ~(1 << cpuid);
 252                         if ((lp->lwp_cpumask & mycpu->gd_cpumask) == 0) {
 253                                 cpuid = bsfl(lp->lwp_cpumask & smp_active_mask);
 254                                 lwkt_migratecpu(cpuid);
 255                         }
 256                 }
 257         default:
 258                 error = EINVAL;
 259                 break;
 260         }
 261         return (error);
 262 }
 263