sys/kern/ksched.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
  33 /* ksched: Soft real time scheduling based on "rtprio".
  34  */
  35
  36 #include <sys/cdefs.h>
  37 __FBSDID("$FreeBSD$");
  38
  39 #include "opt_posix.h"
  40
  41 #include <sys/param.h>
  42 #include <sys/systm.h>
  43 #include <sys/lock.h>
  44 #include <sys/mutex.h>
  45 #include <sys/proc.h>
  46 #include <sys/posix4.h>
  47 #include <sys/resource.h>
  48 #include <sys/sched.h>
  49
  50 /* ksched: Real-time extension to support POSIX priority scheduling.
  51  */
  52
  53 struct ksched {
  54         struct timespec rr_interval;
  55 };
  56
  57 int
  58 ksched_attach(struct ksched **p)
  59 {
  60         struct ksched *ksched= p31b_malloc(sizeof(*ksched));
  61
  62         ksched->rr_interval.tv_sec = 0;
  63         ksched->rr_interval.tv_nsec = 1000000000L / sched_rr_interval();
  64
  65         *p = ksched;
  66         return 0;
  67 }
  68
  69 int
  70 ksched_detach(struct ksched *ks)
  71 {
  72         p31b_free(ks);
  73
  74         return 0;
  75 }
  76
  77 /*
  78  * XXX About priorities
  79  *
  80  *      POSIX 1003.1b requires that numerically higher priorities be of
  81  *      higher priority.  It also permits sched_setparam to be
  82  *      implementation defined for SCHED_OTHER.  I don't like
  83  *      the notion of inverted priorites for normal processes when
  84  *  you can use "setpriority" for that.
  85  *
  86  *      I'm rejecting sched_setparam for SCHED_OTHER with EINVAL.
  87  */
  88
  89 /* Macros to convert between the unix (lower numerically is higher priority)
  90  * and POSIX 1003.1b (higher numerically is higher priority)
  91  */
  92
  93 #define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
  94 #define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
  95
  96 /* These improve readability a bit for me:
  97  */
  98 #define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
  99 #define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
 100
 101 static __inline int
 102 getscheduler(struct ksched *ksched, struct thread *td, int *policy)
 103 {
 104         struct rtprio rtp;
 105         int e = 0;
 106
 107         pri_to_rtp(td, &rtp);
 108         switch (rtp.type)
 109         {
 110                 case RTP_PRIO_FIFO:
 111                 *policy = SCHED_FIFO;
 112                 break;
 113
 114                 case RTP_PRIO_REALTIME:
 115                 *policy = SCHED_RR;
 116                 break;
 117
 118                 default:
 119                 *policy = SCHED_OTHER;
 120                 break;
 121         }
 122
 123         return e;
 124 }
 125
 126 int
 127 ksched_setparam(struct ksched *ksched,
 128     struct thread *td, const struct sched_param *param)
 129 {
 130         int policy;
 131         int e;
 132
 133         e = getscheduler(ksched, td, &policy);
 134
 135         if (e == 0)
 136         {
 137                 if (policy == SCHED_OTHER)
 138                         e = EINVAL;
 139                 else
 140                         e = ksched_setscheduler(ksched, td, policy, param);
 141         }
 142
 143         return e;
 144 }
 145
 146 int
 147 ksched_getparam(struct ksched *ksched,
 148     struct thread *td, struct sched_param *param)
 149 {
 150         struct rtprio rtp;
 151
 152         pri_to_rtp(td, &rtp);
 153         if (RTP_PRIO_IS_REALTIME(rtp.type))
 154                 param->sched_priority = rtpprio_to_p4prio(rtp.prio);
 155
 156         return 0;
 157 }
 158
 159 /*
 160  * XXX The priority and scheduler modifications should
 161  *     be moved into published interfaces in kern/kern_sync.
 162  *
 163  * The permissions to modify process p were checked in "p31b_proc()".
 164  *
 165  */
 166 int
 167 ksched_setscheduler(struct ksched *ksched,
 168     struct thread *td, int policy, const struct sched_param *param)
 169 {
 170         int e = 0;
 171         struct rtprio rtp;
 172
 173         switch(policy)
 174         {
 175                 case SCHED_RR:
 176                 case SCHED_FIFO:
 177
 178                 if (param->sched_priority >= P1B_PRIO_MIN &&
 179                     param->sched_priority <= P1B_PRIO_MAX)
 180                 {
 181                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 182                         rtp.type = (policy == SCHED_FIFO)
 183                                 ? RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
 184
 185                         rtp_to_pri(&rtp, td);
 186                 }
 187                 else
 188                         e = EPERM;
 189
 190
 191                 break;
 192
 193                 case SCHED_OTHER:
 194                 {
 195                         rtp.type = RTP_PRIO_NORMAL;
 196                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 197                         rtp_to_pri(&rtp, td);
 198                 }
 199                 break;
 200
 201                 default:
 202                         e = EINVAL;
 203                         break;
 204         }
 205
 206         return e;
 207 }
 208
 209 int
 210 ksched_getscheduler(struct ksched *ksched, struct thread *td, int *policy)
 211 {
 212         return getscheduler(ksched, td, policy);
 213 }
 214
 215 /* ksched_yield: Yield the CPU.
 216  */
 217 int
 218 ksched_yield(struct ksched *ksched)
 219 {
 220         sched_relinquish(curthread);
 221         return 0;
 222 }
 223
 224 int
 225 ksched_get_priority_max(struct ksched *ksched, int policy, int *prio)
 226 {
 227         int e = 0;
 228
 229         switch (policy)
 230         {
 231                 case SCHED_FIFO:
 232                 case SCHED_RR:
 233                 *prio = RTP_PRIO_MAX;
 234                 break;
 235
 236                 case SCHED_OTHER:
 237                 *prio = PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE;
 238                 break;
 239
 240                 default:
 241                 e = EINVAL;
 242         }
 243
 244         return e;
 245 }
 246
 247 int
 248 ksched_get_priority_min(struct ksched *ksched, int policy, int *prio)
 249 {
 250         int e = 0;
 251
 252         switch (policy)
 253         {
 254                 case SCHED_FIFO:
 255                 case SCHED_RR:
 256                 *prio = P1B_PRIO_MIN;
 257                 break;
 258
 259                 case SCHED_OTHER:
 260                 *prio = 0;
 261                 break;
 262
 263                 default:
 264                 e = EINVAL;
 265         }
 266
 267         return e;
 268 }
 269
 270 int
 271 ksched_rr_get_interval(struct ksched *ksched,
 272    struct thread *td, struct timespec *timespec)
 273 {
 274         *timespec = ksched->rr_interval;
 275
 276         return 0;
 277 }