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 1.6 2005/11/14 18:50:00 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/proc.h>
  42 #include <sys/kernel.h>
  43 #include <sys/resource.h>
  44 #include <machine/cpu.h>        /* For need_user_resched */
  45 #include <machine/ipl.h>        /* For need_user_resched */
  46
  47 #include "posix4.h"
  48
  49 /* ksched: Real-time extension to support POSIX priority scheduling.
  50  */
  51
  52 struct ksched {
  53         struct timespec rr_interval;
  54 };
  55
  56 int 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 ksched_detach(struct ksched *p)
  68 {
  69         p31b_free(p);
  70
  71         return 0;
  72 }
  73
  74 /*
  75  * XXX About priorities
  76  *
  77  *      POSIX 1003.1b requires that numerically higher priorities be of
  78  *      higher priority.  It also permits sched_setparam to be
  79  *      implementation defined for SCHED_OTHER.  I don't like
  80  *      the notion of inverted priorites for normal processes when
  81  *  you can use "setpriority" for that.
  82  *
  83  *      I'm rejecting sched_setparam for SCHED_OTHER with EINVAL.
  84  */
  85
  86 /* Macros to convert between the unix (lower numerically is higher priority)
  87  * and POSIX 1003.1b (higher numerically is higher priority)
  88  */
  89
  90 #define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
  91 #define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
  92
  93 /* These improve readability a bit for me:
  94  */
  95 #define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
  96 #define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
  97
  98 static __inline int
  99 getscheduler(register_t *ret, struct ksched *ksched, struct proc *p)
 100 {
 101         int e = 0;
 102
 103         switch (p->p_lwp.lwp_rtprio.type)
 104         {
 105                 case RTP_PRIO_FIFO:
 106                 *ret = SCHED_FIFO;
 107                 break;
 108
 109                 case RTP_PRIO_REALTIME:
 110                 *ret = SCHED_RR;
 111                 break;
 112
 113                 default:
 114                 *ret = SCHED_OTHER;
 115                 break;
 116         }
 117
 118         return e;
 119 }
 120
 121 int ksched_setparam(register_t *ret, struct ksched *ksched,
 122         struct proc *p, const struct sched_param *param)
 123 {
 124         register_t policy;
 125         int e;
 126
 127         e = getscheduler(&policy, ksched, p);
 128
 129         if (e == 0)
 130         {
 131                 if (policy == SCHED_OTHER)
 132                         e = EINVAL;
 133                 else
 134                         e = ksched_setscheduler(ret, ksched, p, policy, param);
 135         }
 136
 137         return e;
 138 }
 139
 140 int ksched_getparam(register_t *ret, struct ksched *ksched,
 141         struct proc *p, struct sched_param *param)
 142 {
 143         if (RTP_PRIO_IS_REALTIME(p->p_lwp.lwp_rtprio.type))
 144                 param->sched_priority = rtpprio_to_p4prio(p->p_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 ksched_setscheduler(register_t *ret, struct ksched *ksched,
 157         struct proc *p, int policy, const struct sched_param *param)
 158 {
 159         int e = 0;
 160         struct rtprio rtp;
 161
 162         switch(policy)
 163         {
 164                 case SCHED_RR:
 165                 case SCHED_FIFO:
 166
 167                 if (param->sched_priority >= P1B_PRIO_MIN &&
 168                 param->sched_priority <= P1B_PRIO_MAX)
 169                 {
 170                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 171                         rtp.type = (policy == SCHED_FIFO)
 172                                 ? RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
 173
 174                         p->p_lwp.lwp_rtprio = rtp;
 175                         need_user_resched();
 176                 }
 177                 else
 178                         e = EPERM;
 179
 180
 181                 break;
 182
 183                 case SCHED_OTHER:
 184                 {
 185                         rtp.type = RTP_PRIO_NORMAL;
 186                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
 187                         p->p_lwp.lwp_rtprio = rtp;
 188
 189                         /* XXX Simply revert to whatever we had for last
 190                          *     normal scheduler priorities.
 191                          *     This puts a requirement
 192                          *     on the scheduling code: You must leave the
 193                          *     scheduling info alone.
 194                          */
 195                         need_user_resched();
 196                 }
 197                 break;
 198         }
 199
 200         return e;
 201 }
 202
 203 int ksched_getscheduler(register_t *ret, struct ksched *ksched, struct proc *p)
 204 {
 205         return getscheduler(ret, ksched, p);
 206 }
 207
 208 /* ksched_yield: Yield the CPU.
 209  */
 210 int ksched_yield(register_t *ret, struct ksched *ksched)
 211 {
 212         need_user_resched();
 213         return 0;
 214 }
 215
 216 int ksched_get_priority_max(register_t*ret, struct ksched *ksched, int policy)
 217 {
 218         int e = 0;
 219
 220         switch (policy)
 221         {
 222                 case SCHED_FIFO:
 223                 case SCHED_RR:
 224                 *ret = RTP_PRIO_MAX;
 225                 break;
 226
 227                 case SCHED_OTHER:
 228                 *ret =  PRIO_MAX;
 229                 break;
 230
 231                 default:
 232                 e = EINVAL;
 233         }
 234
 235         return e;
 236 }
 237
 238 int ksched_get_priority_min(register_t *ret, struct ksched *ksched, int policy)
 239 {
 240         int e = 0;
 241
 242         switch (policy)
 243         {
 244                 case SCHED_FIFO:
 245                 case SCHED_RR:
 246                 *ret = P1B_PRIO_MIN;
 247                 break;
 248
 249                 case SCHED_OTHER:
 250                 *ret =  PRIO_MIN;
 251                 break;
 252
 253                 default:
 254                 e = EINVAL;
 255         }
 256
 257         return e;
 258 }
 259
 260 int ksched_rr_get_interval(register_t *ret, struct ksched *ksched,
 261         struct proc *p, struct timespec *timespec)
 262 {
 263         *timespec = ksched->rr_interval;
 264
 265         return 0;
 266 }