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

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

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