sys/kern/kern_sched.c

   1 /*
   2  * Copyright (c) 1996, 1997
   3  *      HD Associates, Inc.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by HD Associates, Inc
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/sys/posix4/ksched.c,v 1.7.2.1 2000/05/16 06:58:13 dillon Exp $
  33  * $DragonFly: src/sys/kern/kern_sched.c,v 1.10 2008/04/21 15:24:46 dillon Exp $
  34  */
  35
  36 /* ksched: Soft real time scheduling based on "rtprio".
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/systm.h>
  41 #include <sys/posix4.h>
  42 #include <sys/proc.h>
  43 #include <sys/kernel.h>
  44 #include <sys/resource.h>
  45 #include <machine/cpu.h>        /* For need_user_resched */
  46
  47
  48 /* ksched: Real-time extension to support POSIX priority scheduling.
  49  */
  50
  51 struct ksched {
  52         struct timespec rr_interval;
  53 };
  54
  55 int ksched_attach(struct ksched **p)
  56 {
  57         struct ksched *ksched= p31b_malloc(sizeof(*ksched));
  58
  59         ksched->rr_interval.tv_sec = 0;
  60         ksched->rr_interval.tv_nsec = 1000000000L / 10; /* XXX */
  61
  62         *p = ksched;
  63         return 0;
  64 }
  65
  66 int ksched_detach(struct ksched *p)
  67 {
  68         p31b_free(p);
  69
  70         return 0;
  71 }
  72
  73 /*
  74  * XXX About priorities
  75  *
  76  *      POSIX 1003.1b requires that numerically higher priorities be of
  77  *      higher priority.  It also permits sched_setparam to be
  78  *      implementation defined for SCHED_OTHER.  I don't like
  79  *      the notion of inverted priorites for normal processes when
  80  *  you can use "setpriority" for that.
  81  *
  82  *      I'm rejecting sched_setparam for SCHED_OTHER with EINVAL.
  83  */
  84
  85 /* Macros to convert between the unix (lower numerically is higher priority)
  86  * and POSIX 1003.1b (higher numerically is higher priority)
  87  */
  88
  89 #define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
  90 #define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
  91
  92 /* These improve readability a bit for me:
  93  */
  94 #define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
  95 #define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
  96
  97 static __inline int
  98 getscheduler(register_t *ret, struct ksched *ksched, struct lwp *lp)
  99 {
 100         int e = 0;
 101
 102         switch (lp->lwp_rtprio.type)
 103         {
 104                 case RTP_PRIO_FIFO:
 105                 *ret = SCHED_FIFO;
 106                 break;
 107
 108                 case RTP_PRIO_REALTIME:
 109                 *ret = SCHED_RR;
 110                 break;
 111
 112                 default:
 113                 *ret = SCHED_OTHER;
 114                 break;
 115         }
 116
 117         return e;
 118 }
 119
 120 int ksched_setparam(register_t *ret, struct ksched *ksched,
 121         struct lwp *lp, const struct sched_param *param)
 122 {
 123         register_t policy;
 124         int e;
 125
 126         e = getscheduler(&policy, ksched, lp);
 127
 128         if (e == 0)
 129         {
 130                 if (policy == SCHED_OTHER)
 131                         e = EINVAL;
 132                 else
 133                         e = ksched_setscheduler(ret, ksched, lp, policy, param);
 134         }
 135
 136         return e;
 137 }
 138
 139 int ksched_getparam(register_t *ret, struct ksched *ksched,
 140         struct lwp *lp, struct sched_param *param)
 141 {
 142         if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type))
 143                 param->sched_priority = rtpprio_to_p4prio(lp->lwp_rtprio.prio);
 144
 145         return 0;
 146 }
 147
 148 /*
 149  * XXX The priority and scheduler modifications should
 150  *     be moved into published interfaces in kern/kern_sync.
 151  *
 152  * The permissions to modify process p were checked in "p31b_proc()".
 153  *
 154  */
 155 int ksched_setscheduler(register_t *ret, struct ksched *ksched,
 156         struct lwp *lp, int policy, const struct sched_param *param)
 157 {
 158         int e = 0;
 159         struct rtprio rtp;
 160
 161         switch(policy)
 162         {
 163                 case SCHED_RR:
 164                 case SCHED_FIFO:
 165
 166                 if (param->sched_priority >= P1B_PRIO_MIN &&
 167                 param->sched_priority <= P1B_PRIO_MAX)
 168                 {
 169                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 170                         rtp.type = (policy == SCHED_FIFO)
 171                                 ? RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
 172
 173                         lp->lwp_rtprio = rtp;
 174                         need_user_resched();
 175                 }
 176                 else
 177                         e = EPERM;
 178
 179
 180                 break;
 181
 182                 case SCHED_OTHER:
 183                 {
 184                         rtp.type = RTP_PRIO_NORMAL;
 185                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 186                         lp->lwp_rtprio = rtp;
 187
 188                         /* XXX Simply revert to whatever we had for last
 189                          *     normal scheduler priorities.
 190                          *     This puts a requirement
 191                          *     on the scheduling code: You must leave the
 192                          *     scheduling info alone.
 193                          */
 194                         need_user_resched();
 195                 }
 196                 break;
 197         }
 198
 199         return e;
 200 }
 201
 202 int ksched_getscheduler(register_t *ret, struct ksched *ksched, struct lwp *lp)
 203 {
 204         return getscheduler(ret, ksched, lp);
 205 }
 206
 207 /*
 208  * ksched_yield: Yield the CPU.
 209  *
 210  * MPSAFE
 211  */
 212 int
 213 ksched_yield(register_t *ret, struct ksched *ksched)
 214 {
 215         struct lwp *lp;
 216
 217         if ((lp = curthread->td_lwp) != NULL) {
 218                 lp->lwp_proc->p_usched->yield(lp);
 219         }
 220         return 0;
 221 }
 222
 223 /*
 224  * MPSAFE
 225  */
 226 int
 227 ksched_get_priority_max(register_t*ret, struct ksched *ksched, int policy)
 228 {
 229         int e = 0;
 230
 231         switch (policy) {
 232         case SCHED_FIFO:
 233         case SCHED_RR:
 234                 *ret = RTP_PRIO_MAX;
 235                 break;
 236         case SCHED_OTHER:
 237                 *ret =  PRIO_MAX;
 238                 break;
 239         default:
 240                 e = EINVAL;
 241                 break;
 242         }
 243
 244         return e;
 245 }
 246
 247 /*
 248  * MPSAFE
 249  */
 250 int
 251 ksched_get_priority_min(register_t *ret, struct ksched *ksched, int policy)
 252 {
 253         int e = 0;
 254
 255         switch (policy) {
 256         case SCHED_FIFO:
 257         case SCHED_RR:
 258                 *ret = P1B_PRIO_MIN;
 259                 break;
 260         case SCHED_OTHER:
 261                 *ret =  PRIO_MIN;
 262                 break;
 263         default:
 264                 e = EINVAL;
 265                 break;
 266         }
 267         return e;
 268 }
 269
 270 /*
 271  * MPSAFE
 272  */
 273 int
 274 ksched_rr_get_interval(register_t *ret, struct ksched *ksched,
 275                        struct lwp *lp, struct timespec *timespec)
 276 {
 277         *timespec = ksched->rr_interval;
 278
 279         return 0;
 280 }