Return to ipc_sched.c CVS log

Up to [Apple Darwin 0.x] / kernel / kern

Annotation of kernel/kern/ipc_sched.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* 
        !            26:  * Mach Operating System
        !            27:  * Copyright (c) 1993, 1992,1991,1990 Carnegie Mellon University
        !            28:  * All Rights Reserved.
        !            29:  * 
        !            30:  * Permission to use, copy, modify and distribute this software and its
        !            31:  * documentation is hereby granted, provided that both the copyright
        !            32:  * notice and this permission notice appear in all copies of the
        !            33:  * software, derivative works or modified versions, and any portions
        !            34:  * thereof, and that both notices appear in supporting documentation.
        !            35:  * 
        !            36:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            37:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            38:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            39:  * 
        !            40:  * Carnegie Mellon requests users of this software to return to
        !            41:  * 
        !            42:  *  Software Distribution Coordinator  or  [email protected]
        !            43:  *  School of Computer Science
        !            44:  *  Carnegie Mellon University
        !            45:  *  Pittsburgh PA 15213-3890
        !            46:  * 
        !            47:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            48:  * the rights to redistribute these changes.
        !            49:  */
        !            50: 
        !            51: #include <cpus.h>
        !            52: #include <mach_host.h>
        !            53: 
        !            54: #include <mach/message.h>
        !            55: #include <kern/counters.h>
        !            56: #include <kern/cpu_number.h>
        !            57: #include <kern/lock.h>
        !            58: #include <kern/thread.h>
        !            59: #include <kern/sched_prim.h>
        !            60: #include <kern/processor.h>
        !            61: #include <kern/time_out.h>
        !            62: #include <kern/thread_swap.h>
        !            63: #include <kern/ipc_sched.h>
        !            64: #include <machine/machspl.h>   /* for splsched/splx */
        !            65: #include <machine/pmap.h>
        !            66: 
        !            67: #import <kern/assert.h>
        !            68: 
        !            69: 
        !            70: /*
        !            71:  *     These functions really belong in kern/sched_prim.c.
        !            72:  */
        !            73: 
        !            74: /*
        !            75:  *     Routine:        thread_go
        !            76:  *     Purpose:
        !            77:  *             Start a thread running.
        !            78:  *     Conditions:
        !            79:  *             IPC locks may be held.
        !            80:  */
        !            81: 
        !            82: void
        !            83: thread_go(
        !            84:        thread_t thread)
        !            85: {
        !            86:        int     state;
        !            87:        spl_t   s;
        !            88: 
        !            89:        s = splsched();
        !            90:        thread_lock(thread);
        !            91: 
        !            92:        reset_timeout_check(&thread->timer);
        !            93: 
        !            94:        state = thread->state;
        !            95:        switch (state & TH_SCHED_STATE) {
        !            96: 
        !            97:            case TH_WAIT | TH_SUSP | TH_UNINT:
        !            98:            case TH_WAIT           | TH_UNINT:
        !            99:            case TH_WAIT:
        !           100:                /*
        !           101:                 *      Sleeping and not suspendable - put
        !           102:                 *      on run queue.
        !           103:                 */
        !           104:                thread->state = (state &~ TH_WAIT) | TH_RUN;
        !           105:                thread->wait_result = THREAD_AWAKENED;
        !           106:                thread_setrun(thread, TRUE);
        !           107:                break;
        !           108: 
        !           109:            case          TH_WAIT | TH_SUSP:
        !           110:            case TH_RUN | TH_WAIT:
        !           111:            case TH_RUN | TH_WAIT | TH_SUSP:
        !           112:            case TH_RUN | TH_WAIT           | TH_UNINT:
        !           113:            case TH_RUN | TH_WAIT | TH_SUSP | TH_UNINT:
        !           114:                /*
        !           115:                 *      Either already running, or suspended.
        !           116:                 */
        !           117:                thread->state = state & ~TH_WAIT;
        !           118:                thread->wait_result = THREAD_AWAKENED;
        !           119:                break;
        !           120: 
        !           121:            default:
        !           122:                /*
        !           123:                 *      Not waiting.
        !           124:                 */
        !           125:                break;
        !           126:        }
        !           127: 
        !           128:        thread_unlock(thread);
        !           129:        splx(s);
        !           130: }
        !           131: 
        !           132: /*
        !           133:  *     Routine:        thread_go_and_switch
        !           134:  *     Purpose:
        !           135:  *             Start a thread running.
        !           136:  *     Conditions:
        !           137:  *             No IPC locks held.
        !           138:  */
        !           139: 
        !           140: void
        !           141: thread_go_and_switch(
        !           142:        continuation_t continuation,
        !           143:        thread_t thread)
        !           144: {
        !           145:        int     state;
        !           146:        spl_t   s;
        !           147: 
        !           148:        s = splsched();
        !           149:        thread_lock(thread);
        !           150: 
        !           151:        reset_timeout_check(&thread->timer);
        !           152: 
        !           153:        state = thread->state;
        !           154:        switch (state & TH_SCHED_STATE) {
        !           155: 
        !           156:            case TH_WAIT | TH_SUSP | TH_UNINT:
        !           157:            case TH_WAIT           | TH_UNINT:
        !           158:            case TH_WAIT:
        !           159:                /*
        !           160:                 *      Sleeping and not suspendable - put
        !           161:                 *      on run queue.
        !           162:                 */
        !           163:                thread->state = (state &~ TH_WAIT) | TH_RUN;
        !           164:                thread->wait_result = THREAD_AWAKENED;
        !           165:                if ((thread->processor_set->idle_count > 0) ||
        !           166:                    (thread->processor_set !=
        !           167:                     current_thread()->processor_set)) {
        !           168:                        /*
        !           169:                         *      Other cpus can/must run thread.
        !           170:                         *      Put it on the run queues.
        !           171:                         */
        !           172:                        thread_setrun(thread, TRUE);
        !           173:                        break;
        !           174:                }
        !           175:                else {
        !           176:                    /*
        !           177:                     *  Switch immediately to new thread.
        !           178:                     */
        !           179:                    thread_unlock(thread);
        !           180:                    thread_run(continuation, thread);
        !           181:                    splx(s);
        !           182:                    return;
        !           183:                }
        !           184:                break;
        !           185: 
        !           186:            case          TH_WAIT | TH_SUSP:
        !           187:            case TH_RUN | TH_WAIT:
        !           188:            case TH_RUN | TH_WAIT | TH_SUSP:
        !           189:            case TH_RUN | TH_WAIT           | TH_UNINT:
        !           190:            case TH_RUN | TH_WAIT | TH_SUSP | TH_UNINT:
        !           191:                /*
        !           192:                 *      Either already running, or suspended.
        !           193:                 */
        !           194:                thread->state = state & ~TH_WAIT;
        !           195:                thread->wait_result = THREAD_AWAKENED;
        !           196:                break;
        !           197: 
        !           198:            default:
        !           199:                /*
        !           200:                 *      Not waiting.
        !           201:                 */
        !           202:                break;
        !           203:        }
        !           204: 
        !           205:        thread_unlock(thread);
        !           206:        if (continuation != (void (*)()) 0) {
        !           207:            (void) spl0();
        !           208:            call_continuation(continuation);
        !           209:        }
        !           210:        splx(s);
        !           211: }
        !           212: 
        !           213: /*
        !           214:  *     Routine:        thread_will_wait
        !           215:  *     Purpose:
        !           216:  *             Assert that the thread intends to block.
        !           217:  */
        !           218: 
        !           219: void
        !           220: thread_will_wait(
        !           221:        thread_t thread)
        !           222: {
        !           223:        spl_t   s;
        !           224: 
        !           225:        s = splsched();
        !           226:        thread_lock(thread);
        !           227: 
        !           228:        assert(thread->wait_result = -1);       /* for later assertions */
        !           229:        thread->state |= TH_WAIT;
        !           230: 
        !           231:        thread_unlock(thread);
        !           232:        splx(s);
        !           233: }
        !           234: 
        !           235: /*
        !           236:  *     Routine:        thread_will_wait_with_timeout
        !           237:  *     Purpose:
        !           238:  *             Assert that the thread intends to block,
        !           239:  *             with a timeout.
        !           240:  */
        !           241: 
        !           242: void
        !           243: thread_will_wait_with_timeout(
        !           244:        thread_t thread,
        !           245:        mach_msg_timeout_t msecs)
        !           246: {
        !           247:        natural_t ticks = convert_ipc_timeout_to_ticks(msecs);
        !           248:        spl_t   s;
        !           249: 
        !           250:        s = splsched();
        !           251:        thread_lock(thread);
        !           252: 
        !           253:        assert(thread->wait_result = -1);       /* for later assertions */
        !           254:        thread->state |= TH_WAIT;
        !           255: 
        !           256:        if (ticks != 0 || msecs == 0)
        !           257:                set_timeout(&thread->timer, ticks);
        !           258: 
        !           259:        thread_unlock(thread);
        !           260:        splx(s);
        !           261: }
        !           262: 
        !           263: #if    MACH_HOST
        !           264: #define check_processor_set(thread)    \
        !           265:            (current_processor()->processor_set == (thread)->processor_set)
        !           266: #else  /* MACH_HOST */
        !           267: #define        check_processor_set(thread)     TRUE
        !           268: #endif /* MACH_HOST */
        !           269: 
        !           270: #if    NCPUS > 1
        !           271: #define        check_bound_processor(thread) \
        !           272:            ((thread)->bound_processor == PROCESSOR_NULL || \
        !           273:             (thread)->bound_processor == current_processor())
        !           274: #else  /* NCPUS > 1 */
        !           275: #define        check_bound_processor(thread)   TRUE
        !           276: #endif /* NCPUS > 1 */
        !           277: 
        !           278: /*
        !           279:  *     Routine:        thread_handoff
        !           280:  *     Purpose:
        !           281:  *             Switch to a new thread (new), leaving the current
        !           282:  *             thread (old) blocked.  If successful, moves the
        !           283:  *             kernel stack from old to new and returns as the
        !           284:  *             new thread.  An explicit continuation for the old thread
        !           285:  *             must be supplied.
        !           286:  *
        !           287:  *             NOTE:  Although we wakeup new, we don't set new->wait_result.
        !           288:  *     Returns:
        !           289:  *             TRUE if the handoff happened.
        !           290:  */
        !           291: 
        !           292: boolean_t
        !           293: thread_handoff(
        !           294:        register thread_t old,
        !           295:        register continuation_t continuation,
        !           296:        register thread_t new)
        !           297: {
        !           298:        spl_t   s;
        !           299: 
        !           300:        assert(current_thread() == old);
        !           301: 
        !           302:        /*
        !           303:         *      XXX Dubious things here:
        !           304:         *      I don't check the idle_count on the processor set.
        !           305:         *      No scheduling priority or policy checks.
        !           306:         *      I assume the new thread is interruptible.
        !           307:         */
        !           308: 
        !           309:        s = splsched();
        !           310:        thread_lock(new);
        !           311: 
        !           312:        /*
        !           313:         *      The first thing we must do is check the state
        !           314:         *      of the threads, to ensure we can handoff.
        !           315:         *      This check uses current_processor()->processor_set,
        !           316:         *      which we can read without locking.
        !           317:         */
        !           318: 
        !           319:        if ((old->stack_privilege == current_stack()) ||
        !           320:            (new->state != (TH_WAIT|TH_SWAPPED)) ||
        !           321:             !check_processor_set(new) ||
        !           322:             !check_bound_processor(new)) {
        !           323:                thread_unlock(new);
        !           324:                (void) splx(s);
        !           325: 
        !           326:                counter_always(c_thread_handoff_misses++);
        !           327:                return FALSE;
        !           328:        }
        !           329: 
        !           330:        reset_timeout_check(&new->timer);
        !           331: 
        !           332:        new->state = TH_RUN;
        !           333:        thread_unlock(new);
        !           334: 
        !           335: #if    NCPUS > 1
        !           336:        new->last_processor = current_processor();
        !           337: #endif /* NCPUS > 1 */
        !           338: 
        !           339:        ast_context(new, cpu_number());
        !           340:        timer_switch(&new->system_timer);
        !           341: 
        !           342:        /*
        !           343:         *      stack_handoff is machine-dependent.  It does the
        !           344:         *      machine-dependent components of a context-switch, like
        !           345:         *      changing address spaces.  It updates active_threads.
        !           346:         */
        !           347: 
        !           348:        stack_handoff(old, new);
        !           349: 
        !           350:        /*
        !           351:         *      Now we must dispose of the old thread.
        !           352:         *      This is like thread_continue, except
        !           353:         *      that the old thread isn't waiting yet.
        !           354:         */
        !           355: 
        !           356:        thread_lock(old);
        !           357:        old->swap_func = continuation;
        !           358:        assert(old->wait_result = -1);          /* for later assertions */
        !           359: 
        !           360:        if (old->state == TH_RUN) {
        !           361:                /*
        !           362:                 *      This is our fast path.
        !           363:                 */
        !           364: 
        !           365:                old->state = TH_WAIT|TH_SWAPPED;
        !           366:        }
        !           367:        else if (old->state == (TH_RUN|TH_SUSP)) {
        !           368:                /*
        !           369:                 *      Somebody is trying to suspend the thread.
        !           370:                 */
        !           371: 
        !           372:                old->state = TH_WAIT|TH_SUSP|TH_SWAPPED;
        !           373:                if (old->wake_active) {
        !           374:                        /*
        !           375:                         *      Someone wants to know when the thread
        !           376:                         *      really stops.
        !           377:                         */
        !           378:                        old->wake_active = FALSE;
        !           379:                        thread_unlock(old);
        !           380:                        thread_wakeup((event_t)&old->wake_active);
        !           381:                        goto after_old_thread;
        !           382:                }
        !           383:        } else
        !           384:                panic("thread_handoff");
        !           385: 
        !           386:        thread_unlock(old);
        !           387:     after_old_thread:
        !           388:        (void) splx(s);
        !           389: 
        !           390:        counter_always(c_thread_handoff_hits++);
        !           391:        return TRUE;
        !           392: }

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