The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/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 /* ksched: Soft real time scheduling based on "rtprio".
   34  */
   35 
   36 #include <sys/cdefs.h>
   37 __FBSDID("$FreeBSD: releng/10.1/sys/kern/ksched.c 239183 2012-08-10 18:19:57Z mav $");
   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/sysctl.h>
   45 #include <sys/kernel.h>
   46 #include <sys/mutex.h>
   47 #include <sys/proc.h>
   48 #include <sys/posix4.h>
   49 #include <sys/resource.h>
   50 #include <sys/sched.h>
   51 
   52 FEATURE(kposix_priority_scheduling, "POSIX P1003.1B realtime extensions");
   53 
   54 /* ksched: Real-time extension to support POSIX priority scheduling.
   55  */
   56 
   57 struct ksched {
   58         struct timespec rr_interval;
   59 };
   60 
   61 int
   62 ksched_attach(struct ksched **p)
   63 {
   64         struct ksched *ksched= p31b_malloc(sizeof(*ksched));
   65 
   66         ksched->rr_interval.tv_sec = 0;
   67         ksched->rr_interval.tv_nsec = 1000000000L / hz * sched_rr_interval();
   68 
   69         *p = ksched;
   70         return 0;
   71 }
   72 
   73 int
   74 ksched_detach(struct ksched *ks)
   75 {
   76         p31b_free(ks);
   77 
   78         return 0;
   79 }
   80 
   81 /*
   82  * XXX About priorities
   83  *
   84  *      POSIX 1003.1b requires that numerically higher priorities be of
   85  *      higher priority.  It also permits sched_setparam to be
   86  *      implementation defined for SCHED_OTHER.  I don't like
   87  *      the notion of inverted priorites for normal processes when
   88  *      you can use "setpriority" for that.
   89  *
   90  */
   91 
   92 /* Macros to convert between the unix (lower numerically is higher priority)
   93  * and POSIX 1003.1b (higher numerically is higher priority)
   94  */
   95 
   96 #define p4prio_to_rtpprio(P) (RTP_PRIO_MAX - (P))
   97 #define rtpprio_to_p4prio(P) (RTP_PRIO_MAX - (P))
   98 
   99 #define p4prio_to_tsprio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
  100 #define tsprio_to_p4prio(P) ((PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE) - (P))
  101 
  102 /* These improve readability a bit for me:
  103  */
  104 #define P1B_PRIO_MIN rtpprio_to_p4prio(RTP_PRIO_MAX)
  105 #define P1B_PRIO_MAX rtpprio_to_p4prio(RTP_PRIO_MIN)
  106 
  107 static __inline int
  108 getscheduler(struct ksched *ksched, struct thread *td, int *policy)
  109 {
  110         struct rtprio rtp;
  111         int e = 0;
  112 
  113         pri_to_rtp(td, &rtp);
  114         switch (rtp.type)
  115         {
  116                 case RTP_PRIO_FIFO:
  117                 *policy = SCHED_FIFO;
  118                 break;
  119 
  120                 case RTP_PRIO_REALTIME:
  121                 *policy = SCHED_RR;
  122                 break;
  123 
  124                 default:
  125                 *policy = SCHED_OTHER;
  126                 break;
  127         }
  128 
  129         return e;
  130 }
  131 
  132 int
  133 ksched_setparam(struct ksched *ksched,
  134     struct thread *td, const struct sched_param *param)
  135 {
  136         int policy;
  137         int e;
  138 
  139         e = getscheduler(ksched, td, &policy);
  140 
  141         if (e == 0)
  142         {
  143                         e = ksched_setscheduler(ksched, td, policy, param);
  144         }
  145 
  146         return e;
  147 }
  148 
  149 int
  150 ksched_getparam(struct ksched *ksched,
  151     struct thread *td, struct sched_param *param)
  152 {
  153         struct rtprio rtp;
  154 
  155         pri_to_rtp(td, &rtp);
  156         if (RTP_PRIO_IS_REALTIME(rtp.type))
  157                 param->sched_priority = rtpprio_to_p4prio(rtp.prio);
  158         else {
  159                 if (PRI_MIN_TIMESHARE < rtp.prio) 
  160                         /*
  161                          * The interactive score has it to min realtime
  162                          * so we must show max (64 most likely
  163                          */ 
  164                         param->sched_priority = (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE);
  165                 else
  166                         param->sched_priority = tsprio_to_p4prio(rtp.prio);
  167         }
  168         return 0;
  169 }
  170 
  171 /*
  172  * XXX The priority and scheduler modifications should
  173  *     be moved into published interfaces in kern/kern_sync.
  174  *
  175  * The permissions to modify process p were checked in "p31b_proc()".
  176  *
  177  */
  178 int
  179 ksched_setscheduler(struct ksched *ksched,
  180     struct thread *td, int policy, const struct sched_param *param)
  181 {
  182         int e = 0;
  183         struct rtprio rtp;
  184 
  185         switch(policy)
  186         {
  187                 case SCHED_RR:
  188                 case SCHED_FIFO:
  189 
  190                 if (param->sched_priority >= P1B_PRIO_MIN &&
  191                     param->sched_priority <= P1B_PRIO_MAX)
  192                 {
  193                         rtp.prio = p4prio_to_rtpprio(param->sched_priority);
  194                         rtp.type = (policy == SCHED_FIFO)
  195                                 ? RTP_PRIO_FIFO : RTP_PRIO_REALTIME;
  196 
  197                         rtp_to_pri(&rtp, td);
  198                 }
  199                 else
  200                         e = EPERM;
  201 
  202 
  203                 break;
  204 
  205                 case SCHED_OTHER:
  206                 if (param->sched_priority >= 0 &&
  207                         param->sched_priority <= (PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE)) {
  208                         rtp.type = RTP_PRIO_NORMAL;
  209                         rtp.prio = p4prio_to_tsprio(param->sched_priority);
  210                         rtp_to_pri(&rtp, td);
  211                 } else
  212                         e = EINVAL;
  213 
  214                 break;
  215                 
  216                 default:
  217                         e = EINVAL;
  218                         break;
  219         }
  220 
  221         return e;
  222 }
  223 
  224 int
  225 ksched_getscheduler(struct ksched *ksched, struct thread *td, int *policy)
  226 {
  227         return getscheduler(ksched, td, policy);
  228 }
  229 
  230 /* ksched_yield: Yield the CPU.
  231  */
  232 int
  233 ksched_yield(struct ksched *ksched)
  234 {
  235         sched_relinquish(curthread);
  236         return 0;
  237 }
  238 
  239 int
  240 ksched_get_priority_max(struct ksched *ksched, int policy, int *prio)
  241 {
  242         int e = 0;
  243 
  244         switch (policy)
  245         {
  246                 case SCHED_FIFO:
  247                 case SCHED_RR:
  248                 *prio = RTP_PRIO_MAX;
  249                 break;
  250 
  251                 case SCHED_OTHER:
  252                 *prio = PRI_MAX_TIMESHARE - PRI_MIN_TIMESHARE;
  253                 break;
  254 
  255                 default:
  256                 e = EINVAL;
  257         }
  258 
  259         return e;
  260 }
  261 
  262 int
  263 ksched_get_priority_min(struct ksched *ksched, int policy, int *prio)
  264 {
  265         int e = 0;
  266 
  267         switch (policy)
  268         {
  269                 case SCHED_FIFO:
  270                 case SCHED_RR:
  271                 *prio = P1B_PRIO_MIN;
  272                 break;
  273 
  274                 case SCHED_OTHER:
  275                 *prio = 0;
  276                 break;
  277 
  278                 default:
  279                 e = EINVAL;
  280         }
  281 
  282         return e;
  283 }
  284 
  285 int
  286 ksched_rr_get_interval(struct ksched *ksched,
  287    struct thread *td, struct timespec *timespec)
  288 {
  289         *timespec = ksched->rr_interval;
  290 
  291         return 0;
  292 }

Cache object: 383859838f3c92fbf2890aa395897a1e


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