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
  45 #include <sys/mplock2.h>
  46
  47 #include <machine/smp.h>
  48
  49 static TAILQ_HEAD(, usched) usched_list = TAILQ_HEAD_INITIALIZER(usched_list);
  50
  51 cpumask_t usched_mastermask = -1;
  52
  53 /*
  54  * Called from very low level boot code, i386/i386/machdep.c/init386().
  55  * We cannot do anything fancy.  no malloc's, no nothing other then
  56  * static initialization.
  57  */
  58 struct usched *
  59 usched_init(void)
  60 {
  61         const char *defsched;
  62
  63         defsched = kgetenv("kern.user_scheduler");
  64
  65         /*
  66          * Add various userland schedulers to the system.
  67          */
  68         usched_ctl(&usched_bsd4, USCH_ADD);
  69         usched_ctl(&usched_dummy, USCH_ADD);
  70         if (defsched == NULL )
  71                 return(&usched_bsd4);
  72         if (strcmp(defsched, "bsd4") == 0)
  73                 return(&usched_bsd4);
  74         kprintf("WARNING: Running dummy userland scheduler\n");
  75         return(&usched_dummy);
  76 }
  77
  78 /*
  79  * USCHED_CTL
  80  *
  81  * SYNOPSIS:
  82  *      Add/remove usched to/from list.
  83  *
  84  * ARGUMENTS:
  85  *      usched - pointer to target scheduler
  86  *      action - addition or removal ?
  87  *
  88  * RETURN VALUES:
  89  *      0 - success
  90  *      EINVAL - error
  91  */
  92 int
  93 usched_ctl(struct usched *usched, int action)
  94 {
  95         struct usched *item;    /* temporaly for TAILQ processing */
  96         int error = 0;
  97
  98         switch(action) {
  99         case USCH_ADD:
 100                 /*
 101                  * Make sure it isn't already on the list
 102                  */
 103 #ifdef INVARIANTS
 104                 TAILQ_FOREACH(item, &usched_list, entry) {
 105                         KKASSERT(item != usched);
 106                 }
 107 #endif
 108                 /*
 109                  * Optional callback to the scheduler before we officially
 110                  * add it to the list.
 111                  */
 112                 if (usched->usched_register)
 113                         usched->usched_register();
 114                 TAILQ_INSERT_TAIL(&usched_list, usched, entry);
 115                 break;
 116         case USCH_REM:
 117                 /*
 118                  * Do not allow the default scheduler to be removed
 119                  */
 120                 if (strcmp(usched->name, "bsd4") == 0) {
 121                         error = EINVAL;
 122                         break;
 123                 }
 124                 TAILQ_FOREACH(item, &usched_list, entry) {
 125                         if (item == usched)
 126                                 break;
 127                 }
 128                 if (item) {
 129                         if (item->usched_unregister)
 130                                 item->usched_unregister();
 131                         TAILQ_REMOVE(&usched_list, item, entry);
 132                 } else {
 133                         error = EINVAL;
 134                 }
 135                 break;
 136         default:
 137                 error = EINVAL;
 138                 break;
 139         }
 140         return (error);
 141 }
 142
 143 /*
 144  * USCHED_SET(syscall)
 145  *
 146  * SYNOPSIS:
 147  *      Setting up a proc's usched.
 148  *
 149  * ARGUMENTS:
 150  *      pid     -
 151  *      cmd     -
 152  *      data    -
 153  *      bytes   -
 154  * RETURN VALUES:
 155  *      0 - success
 156  *      EINVAL - error
 157  *
 158  * MPALMOSTSAFE
 159  */
 160 int
 161 sys_usched_set(struct usched_set_args *uap)
 162 {
 163         struct proc *p = curthread->td_proc;
 164         struct usched *item;    /* temporaly for TAILQ processing */
 165         int error;
 166         char buffer[NAME_LENGTH];
 167         cpumask_t mask;
 168         struct lwp *lp;
 169         int cpuid;
 170
 171         if (uap->pid != 0 && uap->pid != curthread->td_proc->p_pid)
 172                 return (EINVAL);
 173
 174         lp = curthread->td_lwp;
 175         get_mplock();
 176
 177         switch (uap->cmd) {
 178         case USCHED_SET_SCHEDULER:
 179                 if ((error = priv_check(curthread, PRIV_SCHED_SET)) != 0)
 180                         break;
 181                 error = copyinstr(uap->data, buffer, sizeof(buffer), NULL);
 182                 if (error)
 183                         break;
 184                 TAILQ_FOREACH(item, &usched_list, entry) {
 185                         if ((strcmp(item->name, buffer) == 0))
 186                                 break;
 187                 }
 188
 189                 /*
 190                  * If the scheduler for a process is being changed, disassociate
 191                  * the old scheduler before switching to the new one.
 192                  *
 193                  * XXX we might have to add an additional ABI call to do a 'full
 194                  * disassociation' and another ABI call to do a 'full
 195                  * reassociation'
 196                  */
 197                 /* XXX lwp have to deal with multiple lwps here */
 198                 if (p->p_nthreads != 1) {
 199                         error = EINVAL;
 200                         break;
 201                 }
 202                 if (item && item != p->p_usched) {
 203                         /* XXX lwp */
 204                         p->p_usched->release_curproc(ONLY_LWP_IN_PROC(p));
 205                         p->p_usched = item;
 206                 } else if (item == NULL) {
 207                         error = EINVAL;
 208                 }
 209                 break;
 210         case USCHED_SET_CPU:
 211                 if ((error = priv_check(curthread, PRIV_SCHED_CPUSET)) != 0)
 212                         break;
 213                 if (uap->bytes != sizeof(int)) {
 214                         error = EINVAL;
 215                         break;
 216                 }
 217                 error = copyin(uap->data, &cpuid, sizeof(int));
 218                 if (error)
 219                         break;
 220                 if (cpuid < 0 || cpuid >= ncpus) {
 221                         error = EFBIG;
 222                         break;
 223                 }
 224                 if ((smp_active_mask & (1 << cpuid)) == 0) {
 225                         error = EINVAL;
 226                         break;
 227                 }
 228                 lp->lwp_cpumask = 1 << cpuid;
 229                 if (cpuid != mycpu->gd_cpuid)
 230                         lwkt_migratecpu(cpuid);
 231                 break;
 232         case USCHED_GET_CPU:
 233                 /* USCHED_GET_CPU doesn't require special privileges. */
 234                 if (uap->bytes != sizeof(int)) {
 235                         error = EINVAL;
 236                         break;
 237                 }
 238                 error = copyout(&(mycpu->gd_cpuid), uap->data, sizeof(int));
 239                 break;
 240         case USCHED_ADD_CPU:
 241                 if ((error = priv_check(curthread, PRIV_SCHED_CPUSET)) != 0)
 242                         break;
 243                 if (uap->bytes != sizeof(int)) {
 244                         error = EINVAL;
 245                         break;
 246                 }
 247                 error = copyin(uap->data, &cpuid, sizeof(int));
 248                 if (error)
 249                         break;
 250                 if (cpuid < 0 || cpuid >= ncpus) {
 251                         error = EFBIG;
 252                         break;
 253                 }
 254                 if (!(smp_active_mask & (1 << cpuid))) {
 255                         error = EINVAL;
 256                         break;
 257                 }
 258                 lp->lwp_cpumask |= 1 << cpuid;
 259                 break;
 260         case USCHED_DEL_CPU:
 261                 /* USCHED_DEL_CPU doesn't require special privileges. */
 262                 if (uap->bytes != sizeof(int)) {
 263                         error = EINVAL;
 264                         break;
 265                 }
 266                 error = copyin(uap->data, &cpuid, sizeof(int));
 267                 if (error)
 268                         break;
 269                 if (cpuid < 0 || cpuid >= ncpus) {
 270                         error = EFBIG;
 271                         break;
 272                 }
 273                 lp = curthread->td_lwp;
 274                 mask = lp->lwp_cpumask & smp_active_mask & ~(1 << cpuid);
 275                 if (mask == 0)
 276                         error = EPERM;
 277                 else {
 278                         lp->lwp_cpumask &= ~(1 << cpuid);
 279                         if ((lp->lwp_cpumask & mycpu->gd_cpumask) == 0) {
 280                                 cpuid = bsfl(lp->lwp_cpumask & smp_active_mask);
 281                                 lwkt_migratecpu(cpuid);
 282                         }
 283                 }
 284                 break;
 285         default:
 286                 error = EINVAL;
 287                 break;
 288         }
 289         rel_mplock();
 290         return (error);
 291 }
 292