ksched.c

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    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  * $FreeBSD$
   33  */
   34 
   35 /* ksched: Soft real time scheduling based on "rtprio".
   36  */
   37 
   38 #include <sys/param.h>
   39 #include <sys/systm.h>
   40 #include <sys/proc.h>
   41 #include <sys/kernel.h>
   42 #include <sys/resource.h>
   43 #include <machine/cpu.h>        /* For need_resched */
   44 #include <machine/ipl.h>        /* For need_resched */
   45 
   46 #include <posix4/posix4.h>
   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 / roundrobin_interval();
   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 proc *p)
   99 {
  100         int e = 0;
  101 
  102         switch (p->p_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 proc *p, const struct sched_param *param)
  122 {
  123         register_t policy;
  124         int e;
  125 
  126         e = getscheduler(&policy, ksched, p);
  127 
  128         if (e == 0)
  129         {
  130                 if (policy == SCHED_OTHER)
  131                         e = EINVAL;
  132                 else
  133                         e = ksched_setscheduler(ret, ksched, p, policy, param);
  134         }
  135 
  136         return e;
  137 }
  138 
  139 int ksched_getparam(register_t *ret, struct ksched *ksched,
  140         struct proc *p, struct sched_param *param)
  141 {
  142         if (RTP_PRIO_IS_REALTIME(p->p_rtprio.type))
  143                 param->sched_priority = rtpprio_to_p4prio(p->p_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 proc *p, 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                         p->p_rtprio = rtp;
  174                         need_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                         p->p_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_resched();
  195                 }
  196                 break;
  197         }
  198 
  199         return e;
  200 }
  201 
  202 int ksched_getscheduler(register_t *ret, struct ksched *ksched, struct proc *p)
  203 {
  204         return getscheduler(ret, ksched, p);
  205 }
  206 
  207 /* ksched_yield: Yield the CPU.
  208  */
  209 int ksched_yield(register_t *ret, struct ksched *ksched)
  210 {
  211         need_resched();
  212         return 0;
  213 }
  214 
  215 int ksched_get_priority_max(register_t*ret, struct ksched *ksched, int policy)
  216 {
  217         int e = 0;
  218 
  219         switch (policy)
  220         {
  221                 case SCHED_FIFO:
  222                 case SCHED_RR:
  223                 *ret = RTP_PRIO_MAX;
  224                 break;
  225 
  226                 case SCHED_OTHER:
  227                 *ret =  PRIO_MAX;
  228                 break;
  229 
  230                 default:
  231                 e = EINVAL;
  232         }
  233 
  234         return e;
  235 }
  236 
  237 int ksched_get_priority_min(register_t *ret, struct ksched *ksched, int policy)
  238 {
  239         int e = 0;
  240 
  241         switch (policy)
  242         {
  243                 case SCHED_FIFO:
  244                 case SCHED_RR:
  245                 *ret = P1B_PRIO_MIN;
  246                 break;
  247 
  248                 case SCHED_OTHER:
  249                 *ret =  PRIO_MIN;
  250                 break;
  251 
  252                 default:
  253                 e = EINVAL;
  254         }
  255 
  256         return e;
  257 }
  258 
  259 int ksched_rr_get_interval(register_t *ret, struct ksched *ksched,
  260         struct proc *p, struct timespec *timespec)
  261 {
  262         *timespec = ksched->rr_interval;
  263 
  264         return 0;
  265 }

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FreeBSD/Linux Kernel Cross Reference sys/posix4/ksched.c

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sys/posix4/ksched.c