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  */
  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
  56 ksched_attach(struct ksched **p)
  57 {
  58         struct ksched *ksched= p31b_malloc(sizeof(*ksched));
  59
  60         ksched->rr_interval.tv_sec = 0;
  61         ksched->rr_interval.tv_nsec = 1000000000L / 10; /* XXX */
  62
  63         *p = ksched;
  64         return 0;
  65 }
  66
  67 int
  68 ksched_detach(struct ksched *p)
  69 {
  70         p31b_free(p);
  71
  72         return 0;
  73 }
  74
  75 /*
  76  * XXX About priorities
  77  *
  78  *      POSIX 1003.1b requires that numerically higher priorities be of
  79  *      higher priority.  It also permits sched_setparam to be
  80  *      implementation defined for SCHED_OTHER.  I don't like
  81  *      the notion of inverted priorites for normal processes when
  82  *      you can use "setpriority" for that.
  83  *
  84  *      I'm rejecting sched_setparam for SCHED_OTHER with EINVAL.
  85  */
  86
  87 /* Macros to convert between the unix (lower numerically is higher priority)
  88  * and POSIX 1003.1b (higher numerically is higher priority)
  89  */
  90
  91 #define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
  92 #define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
  93
  94 /*
  95  * These improve readability a bit for me:
  96  */
  97 #define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
  98 #define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
  99
 100 static __inline int
 101 getscheduler(register_t *ret, struct ksched *ksched, struct lwp *lp)
 102 {
 103         int e = 0;
 104
 105         switch (lp->lwp_rtprio.type) {
 106         case RTP_PRIO_FIFO:
 107                 *ret = SCHED_FIFO;
 108                 break;
 109         case RTP_PRIO_REALTIME:
 110                 *ret = SCHED_RR;
 111                 break;
 112         default:
 113                 *ret = SCHED_OTHER;
 114                 break;
 115         }
 116
 117         return e;
 118 }
 119
 120 int
 121 ksched_setparam(register_t *ret, struct ksched *ksched,
 122     struct lwp *lp, const struct sched_param *param)
 123 {
 124         register_t policy;
 125         int e;
 126
 127         e = getscheduler(&policy, ksched, lp);
 128
 129         if (e == 0) {
 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
 140 ksched_getparam(register_t *ret, struct ksched *ksched,
 141     struct lwp *lp, struct sched_param *param)
 142 {
 143         if (RTP_PRIO_IS_REALTIME(lp->lwp_rtprio.type))
 144                 param->sched_priority = rtpprio_to_p4prio(lp->lwp_rtprio.prio);
 145
 146         return 0;
 147 }
 148
 149 /*
 150  * XXX The priority and scheduler modifications should
 151  *     be moved into published interfaces in kern/kern_sync.
 152  *
 153  * The permissions to modify process p were checked in "p31b_proc()".
 154  *
 155  */
 156 int
 157 ksched_setscheduler(register_t *ret, struct ksched *ksched,
 158     struct lwp *lp, int policy, const struct sched_param *param)
 159 {
 160         int e = 0;
 161         struct rtprio rtp;
 162
 163         switch(policy) {
 164         case SCHED_RR:
 165         case SCHED_FIFO:
 166                 if (param->sched_priority >= P1B_PRIO_MIN &&
 167                     param->sched_priority <= P1B_PRIO_MAX) {
 168                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 169                         rtp.type = (policy == SCHED_FIFO) ?
 170                             RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
 171
 172                         lp->lwp_rtprio = rtp;
 173                         need_user_resched();
 174                 } else {
 175                         e = EINVAL;
 176                 }
 177                 break;
 178         case SCHED_OTHER:
 179                 rtp.type = RTP_PRIO_NORMAL;
 180                 rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 181                 lp->lwp_rtprio = rtp;
 182
 183                 /*
 184                  * XXX Simply revert to whatever we had for last
 185                  *     normal scheduler priorities.
 186                  *     This puts a requirement
 187                  *     on the scheduling code: You must leave the
 188                  *     scheduling info alone.
 189                  */
 190                 need_user_resched();
 191                 break;
 192         }
 193
 194         return e;
 195 }
 196
 197 int
 198 ksched_getscheduler(register_t *ret, struct ksched *ksched, struct lwp *lp)
 199 {
 200         return getscheduler(ret, ksched, lp);
 201 }
 202
 203 /*
 204  * ksched_yield: Yield the CPU.
 205  *
 206  * MPSAFE
 207  */
 208 int
 209 ksched_yield(register_t *ret, struct ksched *ksched)
 210 {
 211         struct lwp *lp;
 212
 213         if ((lp = curthread->td_lwp) != NULL)
 214                 lp->lwp_proc->p_usched->yield(lp);
 215         return 0;
 216 }
 217
 218 /*
 219  * MPSAFE
 220  */
 221 int
 222 ksched_get_priority_max(register_t*ret, struct ksched *ksched, int policy)
 223 {
 224         int e = 0;
 225
 226         switch (policy) {
 227         case SCHED_FIFO:
 228         case SCHED_RR:
 229                 *ret = RTP_PRIO_MAX;
 230                 break;
 231         case SCHED_OTHER:
 232                 *ret =  PRIO_MAX;
 233                 break;
 234         default:
 235                 e = EINVAL;
 236                 break;
 237         }
 238
 239         return e;
 240 }
 241
 242 /*
 243  * MPSAFE
 244  */
 245 int
 246 ksched_get_priority_min(register_t *ret, struct ksched *ksched, int policy)
 247 {
 248         int e = 0;
 249
 250         switch (policy) {
 251         case SCHED_FIFO:
 252         case SCHED_RR:
 253                 *ret = P1B_PRIO_MIN;
 254                 break;
 255         case SCHED_OTHER:
 256                 *ret =  PRIO_MIN;
 257                 break;
 258         default:
 259                 e = EINVAL;
 260                 break;
 261         }
 262         return e;
 263 }
 264
 265 /*
 266  * MPSAFE
 267  */
 268 int
 269 ksched_rr_get_interval(register_t *ret, struct ksched *ksched,
 270     struct lwp *lp, struct timespec *timespec)
 271 {
 272         *timespec = ksched->rr_interval;
 273
 274         return 0;
 275 }