Return to syscall_subr.c CVS log

Up to [GnuMach] / OSKit-Mach / kern

Annotation of OSKit-Mach/kern/syscall_subr.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Mach Operating System
        !             3:  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University.
        !             4:  * Copyright (c) 1993,1994 The University of Utah and
        !             5:  * the Computer Systems Laboratory (CSL).
        !             6:  * All rights reserved.
        !             7:  *
        !             8:  * Permission to use, copy, modify and distribute this software and its
        !             9:  * documentation is hereby granted, provided that both the copyright
        !            10:  * notice and this permission notice appear in all copies of the
        !            11:  * software, derivative works or modified versions, and any portions
        !            12:  * thereof, and that both notices appear in supporting documentation.
        !            13:  *
        !            14:  * CARNEGIE MELLON, THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF
        !            15:  * THIS SOFTWARE IN ITS "AS IS" CONDITION, AND DISCLAIM ANY LIABILITY
        !            16:  * OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF
        !            17:  * THIS SOFTWARE.
        !            18:  *
        !            19:  * Carnegie Mellon requests users of this software to return to
        !            20:  *
        !            21:  *  Software Distribution Coordinator  or  [email protected]
        !            22:  *  School of Computer Science
        !            23:  *  Carnegie Mellon University
        !            24:  *  Pittsburgh PA 15213-3890
        !            25:  *
        !            26:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            27:  * the rights to redistribute these changes.
        !            28:  */
        !            29: 
        !            30: #include <mach_fixpri.h>
        !            31: #include <cpus.h>
        !            32: 
        !            33: #include <mach/boolean.h>
        !            34: #include <mach/thread_switch.h>
        !            35: #include <ipc/ipc_port.h>
        !            36: #include <ipc/ipc_space.h>
        !            37: #include <kern/counters.h>
        !            38: #include <kern/ipc_kobject.h>
        !            39: #include <kern/processor.h>
        !            40: #include <kern/sched.h>
        !            41: #include <kern/sched_prim.h>
        !            42: #include <kern/ipc_sched.h>
        !            43: #include <kern/task.h>
        !            44: #include <kern/thread.h>
        !            45: #include <kern/time_out.h>
        !            46: #include <machine/machspl.h>   /* for splsched */
        !            47: 
        !            48: #if    MACH_FIXPRI
        !            49: #include <mach/policy.h>
        !            50: #endif /* MACH_FIXPRI */
        !            51: 
        !            52: 
        !            53: 
        !            54: /*
        !            55:  *     swtch and swtch_pri both attempt to context switch (logic in
        !            56:  *     thread_block no-ops the context switch if nothing would happen).
        !            57:  *     A boolean is returned that indicates whether there is anything
        !            58:  *     else runnable.
        !            59:  *
        !            60:  *     This boolean can be used by a thread waiting on a
        !            61:  *     lock or condition:  If FALSE is returned, the thread is justified
        !            62:  *     in becoming a resource hog by continuing to spin because there's
        !            63:  *     nothing else useful that the processor could do.  If TRUE is
        !            64:  *     returned, the thread should make one more check on the
        !            65:  *     lock and then be a good citizen and really suspend.
        !            66:  */
        !            67: 
        !            68: extern void thread_depress_priority();
        !            69: extern kern_return_t thread_depress_abort();
        !            70: 
        !            71: #ifdef CONTINUATIONS
        !            72: void swtch_continue()
        !            73: {
        !            74:        register processor_t    myprocessor;
        !            75: 
        !            76:        myprocessor = current_processor();
        !            77:        thread_syscall_return(myprocessor->runq.count > 0 ||
        !            78:                              myprocessor->processor_set->runq.count > 0);
        !            79:        /*NOTREACHED*/
        !            80: }
        !            81: #else  /* not CONTINUATIONS */
        !            82: #define swtch_continue 0
        !            83: #endif /* not CONTINUATIONS */
        !            84: 
        !            85: boolean_t swtch()
        !            86: {
        !            87:        register processor_t    myprocessor;
        !            88: 
        !            89: #if    NCPUS > 1
        !            90:        myprocessor = current_processor();
        !            91:        if (myprocessor->runq.count == 0 &&
        !            92:            myprocessor->processor_set->runq.count == 0)
        !            93:                return(FALSE);
        !            94: #endif /* NCPUS > 1 */
        !            95: 
        !            96:        counter(c_swtch_block++);
        !            97:        thread_block(swtch_continue);
        !            98:        myprocessor = current_processor();
        !            99:        return(myprocessor->runq.count > 0 ||
        !           100:               myprocessor->processor_set->runq.count > 0);
        !           101: }
        !           102: 
        !           103: #ifdef CONTINUATIONS
        !           104: void swtch_pri_continue()
        !           105: {
        !           106:        register thread_t       thread = current_thread();
        !           107:        register processor_t    myprocessor;
        !           108: 
        !           109:        if (thread->depress_priority >= 0)
        !           110:                (void) thread_depress_abort(thread);
        !           111:        myprocessor = current_processor();
        !           112:        thread_syscall_return(myprocessor->runq.count > 0 ||
        !           113:                              myprocessor->processor_set->runq.count > 0);
        !           114:        /*NOTREACHED*/
        !           115: }
        !           116: #else  /* not CONTINUATIONS */
        !           117: #define swtch_pri_continue 0
        !           118: #endif /* not CONTINUATIONS */
        !           119: 
        !           120: boolean_t  swtch_pri(pri)
        !           121:        int pri;
        !           122: {
        !           123:        register thread_t       thread = current_thread();
        !           124:        register processor_t    myprocessor;
        !           125: 
        !           126: #ifdef lint
        !           127:        pri++;
        !           128: #endif /* lint */
        !           129: 
        !           130: #if    NCPUS > 1
        !           131:        myprocessor = current_processor();
        !           132:        if (myprocessor->runq.count == 0 &&
        !           133:            myprocessor->processor_set->runq.count == 0)
        !           134:                return(FALSE);
        !           135: #endif /* NCPUS > 1 */
        !           136: 
        !           137:        /*
        !           138:         *      XXX need to think about depression duration.
        !           139:         *      XXX currently using min quantum.
        !           140:         */
        !           141:        thread_depress_priority(thread, min_quantum);
        !           142: 
        !           143:        counter(c_swtch_pri_block++);
        !           144:        thread_block(swtch_pri_continue);
        !           145: 
        !           146:        if (thread->depress_priority >= 0)
        !           147:                (void) thread_depress_abort(thread);
        !           148:        myprocessor = current_processor();
        !           149:        return(myprocessor->runq.count > 0 ||
        !           150:               myprocessor->processor_set->runq.count > 0);
        !           151: }
        !           152: 
        !           153: extern int hz;
        !           154: 
        !           155: #ifdef CONTINUATIONS
        !           156: void thread_switch_continue()
        !           157: {
        !           158:        register thread_t       cur_thread = current_thread();
        !           159: 
        !           160:        /*
        !           161:         *  Restore depressed priority
        !           162:         */
        !           163:        if (cur_thread->depress_priority >= 0)
        !           164:                (void) thread_depress_abort(cur_thread);
        !           165:        thread_syscall_return(KERN_SUCCESS);
        !           166:        /*NOTREACHED*/
        !           167: }
        !           168: #else  /* not CONTINUATIONS */
        !           169: #define thread_switch_continue 0
        !           170: #endif /* not CONTINUATIONS */
        !           171: 
        !           172: /*
        !           173:  *     thread_switch:
        !           174:  *
        !           175:  *     Context switch.  User may supply thread hint.
        !           176:  *
        !           177:  *     Fixed priority threads that call this get what they asked for
        !           178:  *     even if that violates priority order.
        !           179:  */
        !           180: kern_return_t thread_switch(thread_name, option, option_time)
        !           181: mach_port_t thread_name;
        !           182: int option;
        !           183: mach_msg_timeout_t option_time;
        !           184: {
        !           185:     register thread_t          cur_thread = current_thread();
        !           186:     register processor_t       myprocessor;
        !           187:     ipc_port_t                 port;
        !           188: 
        !           189:     /*
        !           190:      * Process option.
        !           191:      */
        !           192:     switch (option) {
        !           193:        case SWITCH_OPTION_NONE:
        !           194:            /*
        !           195:             *  Nothing to do.
        !           196:             */
        !           197:            break;
        !           198: 
        !           199:        case SWITCH_OPTION_DEPRESS:
        !           200:            /*
        !           201:             *  Depress priority for given time.
        !           202:             */
        !           203:            thread_depress_priority(cur_thread, option_time);
        !           204:            break;
        !           205: 
        !           206:        case SWITCH_OPTION_WAIT:
        !           207:            thread_will_wait_with_timeout(cur_thread, option_time);
        !           208:            break;
        !           209: 
        !           210:        default:
        !           211:            return(KERN_INVALID_ARGUMENT);
        !           212:     }
        !           213: 
        !           214: #ifndef MIGRATING_THREADS /* XXX thread_run defunct */
        !           215:     /*
        !           216:      * Check and act on thread hint if appropriate.
        !           217:      */
        !           218:     if ((thread_name != 0) &&
        !           219:        (ipc_port_translate_send(cur_thread->task->itk_space,
        !           220:                                 thread_name, &port) == KERN_SUCCESS)) {
        !           221:            /* port is locked, but it might not be active */
        !           222: 
        !           223:            /*
        !           224:             *  Get corresponding thread.
        !           225:             */
        !           226:            if (ip_active(port) && (ip_kotype(port) == IKOT_THREAD)) {
        !           227:                register thread_t thread;
        !           228:                register spl_t s;
        !           229: 
        !           230:                thread = (thread_t) port->ip_kobject;
        !           231:                /*
        !           232:                 *      Check if the thread is in the right pset. Then
        !           233:                 *      pull it off its run queue.  If it
        !           234:                 *      doesn't come, then it's not eligible.
        !           235:                 */
        !           236:                s = splsched();
        !           237:                thread_lock(thread);
        !           238:                if ((thread->processor_set == cur_thread->processor_set)
        !           239:                    && (rem_runq(thread) != RUN_QUEUE_NULL)) {
        !           240:                        /*
        !           241:                         *      Hah, got it!!
        !           242:                         */
        !           243:                        thread_unlock(thread);
        !           244:                        (void) splx(s);
        !           245:                        ip_unlock(port);
        !           246:                        /* XXX thread might disappear on us now? */
        !           247: #if    MACH_FIXPRI
        !           248:                        if (thread->policy == POLICY_FIXEDPRI) {
        !           249:                            myprocessor = current_processor();
        !           250:                            myprocessor->quantum = thread->sched_data;
        !           251:                            myprocessor->first_quantum = TRUE;
        !           252:                        }
        !           253: #endif /* MACH_FIXPRI */
        !           254:                        counter(c_thread_switch_handoff++);
        !           255:                        thread_run(thread_switch_continue, thread);
        !           256:                        /*
        !           257:                         *  Restore depressed priority
        !           258:                         */
        !           259:                        if (cur_thread->depress_priority >= 0)
        !           260:                                (void) thread_depress_abort(cur_thread);
        !           261: 
        !           262:                        return(KERN_SUCCESS);
        !           263:                }
        !           264:                thread_unlock(thread);
        !           265:                (void) splx(s);
        !           266:            }
        !           267:            ip_unlock(port);
        !           268:     }
        !           269: #endif /* not MIGRATING_THREADS */
        !           270: 
        !           271:     /*
        !           272:      * No handoff hint supplied, or hint was wrong.  Call thread_block() in
        !           273:      * hopes of running something else.  If nothing else is runnable,
        !           274:      * thread_block will detect this.  WARNING: thread_switch with no
        !           275:      * option will not do anything useful if the thread calling it is the
        !           276:      * highest priority thread (can easily happen with a collection
        !           277:      * of timesharing threads).
        !           278:      */
        !           279: #if    NCPUS > 1
        !           280:     myprocessor = current_processor();
        !           281:     if (myprocessor->processor_set->runq.count > 0 ||
        !           282:        myprocessor->runq.count > 0)
        !           283: #endif /* NCPUS > 1 */
        !           284:     {
        !           285:        counter(c_thread_switch_block++);
        !           286:        thread_block(thread_switch_continue);
        !           287:     }
        !           288: 
        !           289:     /*
        !           290:      *  Restore depressed priority
        !           291:      */
        !           292:     if (cur_thread->depress_priority >= 0)
        !           293:        (void) thread_depress_abort(cur_thread);
        !           294:     return(KERN_SUCCESS);
        !           295: }
        !           296: 
        !           297: /*
        !           298:  *     thread_depress_priority
        !           299:  *
        !           300:  *     Depress thread's priority to lowest possible for specified period.
        !           301:  *     Intended for use when thread wants a lock but doesn't know which
        !           302:  *     other thread is holding it.  As with thread_switch, fixed
        !           303:  *     priority threads get exactly what they asked for.  Users access
        !           304:  *     this by the SWITCH_OPTION_DEPRESS option to thread_switch.  A Time
        !           305:  *      of zero will result in no timeout being scheduled.
        !           306:  */
        !           307: void
        !           308: thread_depress_priority(thread, depress_time)
        !           309: register thread_t thread;
        !           310: mach_msg_timeout_t depress_time;
        !           311: {
        !           312:     unsigned int ticks;
        !           313:     spl_t      s;
        !           314: 
        !           315:     /* convert from milliseconds to ticks */
        !           316:     ticks = convert_ipc_timeout_to_ticks(depress_time);
        !           317: 
        !           318:     s = splsched();
        !           319:     thread_lock(thread);
        !           320: 
        !           321:     /*
        !           322:      * If thread is already depressed, override previous depression.
        !           323:      */
        !           324:     reset_timeout_check(&thread->depress_timer);
        !           325: 
        !           326:     /*
        !           327:      * Save current priority, then set priority and
        !           328:      * sched_pri to their lowest possible values.
        !           329:      */
        !           330:     thread->depress_priority = thread->priority;
        !           331:     thread->priority = 31;
        !           332:     thread->sched_pri = 31;
        !           333:     if (ticks != 0)
        !           334:        set_timeout(&thread->depress_timer, ticks);
        !           335: 
        !           336:     thread_unlock(thread);
        !           337:     (void) splx(s);
        !           338: }
        !           339: 
        !           340: /*
        !           341:  *     thread_depress_timeout:
        !           342:  *
        !           343:  *     Timeout routine for priority depression.
        !           344:  */
        !           345: void
        !           346: thread_depress_timeout(thread)
        !           347: register thread_t thread;
        !           348: {
        !           349:     spl_t      s;
        !           350: 
        !           351:     s = splsched();
        !           352:     thread_lock(thread);
        !           353: 
        !           354:     /*
        !           355:      * If we lose a race with thread_depress_abort,
        !           356:      * then depress_priority might be -1.
        !           357:      */
        !           358: 
        !           359:     if (thread->depress_priority >= 0) {
        !           360:        thread->priority = thread->depress_priority;
        !           361:        thread->depress_priority = -1;
        !           362:        compute_priority(thread, FALSE);
        !           363:     }
        !           364: 
        !           365:     thread_unlock(thread);
        !           366:     (void) splx(s);
        !           367: }
        !           368: 
        !           369: /*
        !           370:  *     thread_depress_abort:
        !           371:  *
        !           372:  *     Prematurely abort priority depression if there is one.
        !           373:  */
        !           374: kern_return_t
        !           375: thread_depress_abort(thread)
        !           376: register thread_t      thread;
        !           377: {
        !           378:     spl_t      s;
        !           379: 
        !           380:     if (thread == THREAD_NULL)
        !           381:        return(KERN_INVALID_ARGUMENT);
        !           382: 
        !           383:     s = splsched();
        !           384:     thread_lock(thread);
        !           385: 
        !           386:     /*
        !           387:      * Only restore priority if thread is depressed.
        !           388:      */
        !           389:     if (thread->depress_priority >= 0) {
        !           390:        reset_timeout_check(&thread->depress_timer);
        !           391:        thread->priority = thread->depress_priority;
        !           392:        thread->depress_priority = -1;
        !           393:        compute_priority(thread, FALSE);
        !           394:     }
        !           395: 
        !           396:     thread_unlock(thread);
        !           397:     (void) splx(s);
        !           398:     return(KERN_SUCCESS);
        !           399: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.