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/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 cpumask_t usched_mastermask = -1;
  48
  49 /*
  50  * Called from very low level boot code, i386/i386/machdep.c/init386().
  51  * We cannot do anything fancy.  no malloc's, no nothing other then
  52  * static initialization.
  53  */
  54 struct usched *
  55 usched_init(void)
  56 {
  57         const char *defsched;
  58
  59         defsched = kgetenv("kern.user_scheduler");
  60
  61         /*
  62          * Add various userland schedulers to the system.
  63          */
  64         usched_ctl(&usched_bsd4, USCH_ADD);
  65         usched_ctl(&usched_dummy, USCH_ADD);
  66         if (defsched == NULL )
  67                 return(&usched_bsd4);
  68         if (strcmp(defsched, "bsd4") == 0)
  69                 return(&usched_bsd4);
  70         kprintf("WARNING: Running dummy userland scheduler\n");
  71         return(&usched_dummy);
  72 }
  73
  74 /*
  75  * USCHED_CTL
  76  *
  77  * SYNOPSIS:
  78  *      Add/remove usched to/from list.
  79  *
  80  * ARGUMENTS:
  81  *      usched - pointer to target scheduler
  82  *      action - addition or removal ?
  83  *
  84  * RETURN VALUES:
  85  *      0 - success
  86  *      EINVAL - error
  87  */
  88 int
  89 usched_ctl(struct usched *usched, int action)
  90 {
  91         struct usched *item;    /* temporaly for TAILQ processing */
  92         int error = 0;
  93
  94         switch(action) {
  95         case USCH_ADD:
  96                 /*
  97                  * Make sure it isn't already on the list
  98                  */
  99 #ifdef INVARIANTS
 100                 TAILQ_FOREACH(item, &usched_list, entry) {
 101                         KKASSERT(item != usched);
 102                 }
 103 #endif
 104                 /*
 105                  * Optional callback to the scheduler before we officially
 106                  * add it to the list.
 107                  */
 108                 if (usched->usched_register)
 109                         usched->usched_register();
 110                 TAILQ_INSERT_TAIL(&usched_list, usched, entry);
 111                 break;
 112         case USCH_REM:
 113                 /*
 114                  * Do not allow the default scheduler to be removed
 115                  */
 116                 if (strcmp(usched->name, "bsd4") == 0) {
 117                         error = EINVAL;
 118                         break;
 119                 }
 120                 TAILQ_FOREACH(item, &usched_list, entry) {
 121                         if (item == usched)
 122                                 break;
 123                 }
 124                 if (item) {
 125                         if (item->usched_unregister)
 126                                 item->usched_unregister();
 127                         TAILQ_REMOVE(&usched_list, item, entry);
 128                 } else {
 129                         error = EINVAL;
 130                 }
 131                 break;
 132         default:
 133                 error = EINVAL;
 134                 break;
 135         }
 136         return (error);
 137 }
 138
 139 /*
 140  * USCHED_SET(syscall)
 141  *
 142  * SYNOPSIS:
 143  *      Setting up a proc's usched.
 144  *
 145  * ARGUMENTS:
 146  *      pid     -
 147  *      cmd     -
 148  *      data    -
 149  *      bytes   -
 150  * RETURN VALUES:
 151  *      0 - success
 152  *      EINVAL - error
 153  */
 154 int
 155 sys_usched_set(struct usched_set_args *uap)
 156 {
 157         struct proc *p = curthread->td_proc;
 158         struct usched *item;    /* temporaly for TAILQ processing */
 159         int error;
 160         char buffer[NAME_LENGTH];
 161         cpumask_t mask;
 162         struct lwp *lp;
 163         int cpuid;
 164
 165         if ((error = suser(curthread)) != 0)
 166                 return (error);
 167
 168         if (uap->pid != 0 && uap->pid != curthread->td_proc->p_pid)
 169                 return (EINVAL);
 170
 171         lp = curthread->td_lwp;
 172         switch (uap->cmd) {
 173         case USCHED_SET_SCHEDULER:
 174                 if ((error = copyinstr(uap->data, buffer, sizeof(buffer),
 175                         NULL)) != 0)
 176                         return (error);
 177                 TAILQ_FOREACH(item, &usched_list, entry) {
 178                         if ((strcmp(item->name, buffer) == 0))
 179                                 break;
 180                 }
 181
 182                 /*
 183                  * If the scheduler for a process is being changed, disassociate
 184                  * the old scheduler before switching to the new one.
 185                  *
 186                  * XXX we might have to add an additional ABI call to do a 'full
 187                  * disassociation' and another ABI call to do a 'full
 188                  * reassociation'
 189                  */
 190                 /* XXX lwp have to deal with multiple lwps here */
 191                 if (p->p_nthreads != 1)
 192                         return (EINVAL);
 193                 if (item && item != p->p_usched) {
 194                         /* XXX lwp */
 195                         p->p_usched->release_curproc(ONLY_LWP_IN_PROC(p));
 196                         p->p_usched = item;
 197                 } else if (item == NULL) {
 198                         error = EINVAL;
 199                 }
 200                 break;
 201         case USCHED_SET_CPU:
 202                 if (uap->bytes != sizeof(int))
 203                         return (EINVAL);
 204                 error = copyin(uap->data, &cpuid, sizeof(int));
 205                 if (error)
 206                         break;
 207                 if (cpuid < 0 || cpuid >= ncpus) {
 208                         error = EFBIG;
 209                         break;
 210                 }
 211                 if ((smp_active_mask & (1 << cpuid)) == 0) {
 212                         error = EINVAL;
 213                         break;
 214                 }
 215                 lp->lwp_cpumask = 1 << cpuid;
 216                 if (cpuid != mycpu->gd_cpuid)
 217                         lwkt_migratecpu(cpuid);
 218                 break;
 219         case USCHED_ADD_CPU:
 220                 if (uap->bytes != sizeof(int))
 221                         return (EINVAL);
 222                 error = copyin(uap->data, &cpuid, sizeof(int));
 223                 if (error)
 224                         break;
 225                 if (cpuid < 0 || cpuid >= ncpus) {
 226                         error = EFBIG;
 227                         break;
 228                 }
 229                 if (!(smp_active_mask & (1 << cpuid))) {
 230                         error = EINVAL;
 231                         break;
 232                 }
 233                 lp->lwp_cpumask |= 1 << cpuid;
 234                 break;
 235         case USCHED_DEL_CPU:
 236                 if (uap->bytes != sizeof(int))
 237                         return (EINVAL);
 238                 error = copyin(uap->data, &cpuid, sizeof(int));
 239                 if (error)
 240                         break;
 241                 if (cpuid < 0 || cpuid >= ncpus) {
 242                         error = EFBIG;
 243                         break;
 244                 }
 245                 lp = curthread->td_lwp;
 246                 mask = lp->lwp_cpumask & smp_active_mask & ~(1 << cpuid);
 247                 if (mask == 0)
 248                         error = EPERM;
 249                 else {
 250                         lp->lwp_cpumask &= ~(1 << cpuid);
 251                         if ((lp->lwp_cpumask & mycpu->gd_cpumask) == 0) {
 252                                 cpuid = bsfl(lp->lwp_cpumask & smp_active_mask);
 253                                 lwkt_migratecpu(cpuid);
 254                         }
 255                 }
 256         default:
 257                 error = EINVAL;
 258                 break;
 259         }
 260         return (error);
 261 }
 262