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 1.8 2007/02/03 18:05:58 corecode Exp $
  35  */
  36
  37 #include <sys/errno.h>
  38 #include <sys/globaldata.h>             /* curthread */
  39 #include <sys/proc.h>
  40 #include <sys/sysproto.h>               /* struct usched_set_args */
  41 #include <sys/systm.h>                  /* strcmp() */
  42 #include <sys/usched.h>
  43 #include <machine/smp.h>
  44
  45 static TAILQ_HEAD(, usched) usched_list = TAILQ_HEAD_INITIALIZER(usched_list);
  46
  47 /*
  48  * Called from very low level boot code, i386/i386/machdep.c/init386().
  49  * We cannot do anything fancy.  no malloc's, no nothing other then
  50  * static initialization.
  51  */
  52 struct usched *
  53 usched_init(void)
  54 {
  55         const char *defsched;
  56
  57         defsched = kgetenv("kern.user_scheduler");
  58
  59         /*
  60          * Add various userland schedulers to the system.
  61          */
  62         usched_ctl(&usched_bsd4, USCH_ADD);
  63         usched_ctl(&usched_dummy, USCH_ADD);
  64         if (defsched == NULL )
  65                 return(&usched_bsd4);
  66         if (strcmp(defsched, "bsd4") == 0)
  67                 return(&usched_bsd4);
  68         kprintf("WARNING: Running dummy userland scheduler\n");
  69         return(&usched_dummy);
  70 }
  71
  72 /*
  73  * USCHED_CTL
  74  *
  75  * SYNOPSIS:
  76  *      Add/remove usched to/from list.
  77  *
  78  * ARGUMENTS:
  79  *      usched - pointer to target scheduler
  80  *      action - addition or removal ?
  81  *
  82  * RETURN VALUES:
  83  *      0 - success
  84  *      EINVAL - error
  85  */
  86 int
  87 usched_ctl(struct usched *usched, int action)
  88 {
  89         struct usched *item;    /* temporaly for TAILQ processing */
  90         int error = 0;
  91
  92         switch(action) {
  93         case USCH_ADD:
  94                 /*
  95                  * Make sure it isn't already on the list
  96                  */
  97 #ifdef INVARIANTS
  98                 TAILQ_FOREACH(item, &usched_list, entry) {
  99                         KKASSERT(item != usched);
 100                 }
 101 #endif
 102                 /*
 103                  * Optional callback to the scheduler before we officially
 104                  * add it to the list.
 105                  */
 106                 if (usched->usched_register)
 107                         usched->usched_register();
 108                 TAILQ_INSERT_TAIL(&usched_list, usched, entry);
 109                 break;
 110         case USCH_REM:
 111                 /*
 112                  * Do not allow the default scheduler to be removed
 113                  */
 114                 if (strcmp(usched->name, "bsd4") == 0) {
 115                         error = EINVAL;
 116                         break;
 117                 }
 118                 TAILQ_FOREACH(item, &usched_list, entry) {
 119                         if (item == usched)
 120                                 break;
 121                 }
 122                 if (item) {
 123                         if (item->usched_unregister)
 124                                 item->usched_unregister();
 125                         TAILQ_REMOVE(&usched_list, item, entry);
 126                 } else {
 127                         error = EINVAL;
 128                 }
 129                 break;
 130         default:
 131                 error = EINVAL;
 132                 break;
 133         }
 134         return (error);
 135 }
 136
 137 /*
 138  * USCHED_SET(syscall)
 139  *
 140  * SYNOPSIS:
 141  *      Setting up a proc's usched.
 142  *
 143  * ARGUMENTS:
 144  *      pid     -
 145  *      cmd     -
 146  *      data    -
 147  *      bytes   -
 148  * RETURN VALUES:
 149  *      0 - success
 150  *      EINVAL - error
 151  */
 152 int
 153 sys_usched_set(struct usched_set_args *uap)
 154 {
 155         struct proc *p = curthread->td_proc;
 156         struct usched *item;    /* temporaly for TAILQ processing */
 157         int error;
 158         char buffer[NAME_LENGTH];
 159         cpumask_t mask;
 160         struct lwp *lp;
 161         int cpuid;
 162
 163         if ((error = suser(curthread)) != 0)
 164                 return (error);
 165
 166         if (uap->pid != 0 && uap->pid != curthread->td_proc->p_pid)
 167                 return (EINVAL);
 168
 169         lp = curthread->td_lwp;
 170         switch (uap->cmd) {
 171         case USCHED_SET_SCHEDULER:
 172                 if ((error = copyinstr(uap->data, buffer, sizeof(buffer),
 173                         NULL)) != 0)
 174                         return (error);
 175                 TAILQ_FOREACH(item, &usched_list, entry) {
 176                         if ((strcmp(item->name, buffer) == 0))
 177                                 break;
 178                 }
 179
 180                 /*
 181                  * If the scheduler for a process is being changed, disassociate
 182                  * the old scheduler before switching to the new one.
 183                  *
 184                  * XXX we might have to add an additional ABI call to do a 'full
 185                  * disassociation' and another ABI call to do a 'full
 186                  * reassociation'
 187                  */
 188                 /* XXX lwp have to deal with multiple lwps here */
 189                 if (p->p_nthreads != 1)
 190                         return (EINVAL);
 191                 if (item && item != p->p_usched) {
 192                         /* XXX lwp */
 193                         p->p_usched->release_curproc(ONLY_LWP_IN_PROC(p));
 194                         p->p_usched = item;
 195                 } else if (item == NULL) {
 196                         error = EINVAL;
 197                 }
 198                 break;
 199         case USCHED_SET_CPU:
 200                 if (uap->bytes != sizeof(int))
 201                         return (EINVAL);
 202                 error = copyin(uap->data, &cpuid, sizeof(int));
 203                 if (error)
 204                         break;
 205                 if ((smp_active_mask & (1 << cpuid)) == 0) {
 206                         error = EINVAL;
 207                         break;
 208                 }
 209                 lp->lwp_cpumask = 1 << cpuid;
 210                 if (cpuid != mycpu->gd_cpuid)
 211                         lwkt_migratecpu(cpuid);
 212                 break;
 213         case USCHED_ADD_CPU:
 214                 if (uap->bytes != sizeof(int))
 215                         return (EINVAL);
 216                 error = copyin(uap->data, &cpuid, sizeof(int));
 217                 if (error)
 218                         break;
 219                 if (!(smp_active_mask & (1 << cpuid))) {
 220                         error = EINVAL;
 221                         break;
 222                 }
 223                 lp->lwp_cpumask |= 1 << cpuid;
 224                 break;
 225         case USCHED_DEL_CPU:
 226                 if (uap->bytes != sizeof(int))
 227                         return (EINVAL);
 228                 error = copyin(uap->data, &cpuid, sizeof(int));
 229                 if (error)
 230                         break;
 231                 lp = curthread->td_lwp;
 232                 mask = lp->lwp_cpumask & smp_active_mask & ~(1 << cpuid);
 233                 if (mask == 0)
 234                         error = EPERM;
 235                 else {
 236                         lp->lwp_cpumask &= ~(1 << cpuid);
 237                         if ((lp->lwp_cpumask & mycpu->gd_cpumask) == 0) {
 238                                 cpuid = bsfl(lp->lwp_cpumask & smp_active_mask);
 239                                 lwkt_migratecpu(cpuid);
 240                         }
 241                 }
 242         default:
 243                 error = EINVAL;
 244                 break;
 245         }
 246         return (error);
 247 }
 248