Return to ast.c CVS log

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

Annotation of kernel/kern/ast.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) 1991,1990,1989,1988,1987 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:  *
        !            52:  *     This file contains routines to check whether an ast is needed.
        !            53:  *
        !            54:  *     ast_check() - check whether ast is needed for interrupt or context
        !            55:  *     switch.  Usually called by clock interrupt handler.
        !            56:  *
        !            57:  */
        !            58: 
        !            59: #include <cpus.h>
        !            60: #include <mach_fixpri.h>
        !            61: 
        !            62: #include <kern/ast.h>
        !            63: #include <kern/counters.h>
        !            64: #include <kern/cpu_number.h>
        !            65: #include <kern/queue.h>
        !            66: #include <kern/sched.h>
        !            67: #include <kern/sched_prim.h>
        !            68: #include <kern/thread.h>
        !            69: #include <kern/processor.h>
        !            70: #include <machine/machspl.h>   /* for splsched */
        !            71: 
        !            72: #include <sys/param.h>         /* XXX */
        !            73: #include <sys/proc.h>          /* XXX */
        !            74: #include <sys/user.h>          /* XXX */
        !            75: #include <sys/signalvar.h>
        !            76: 
        !            77: #if    MACH_FIXPRI
        !            78: #include <mach/policy.h>
        !            79: #endif MACH_FIXPRI
        !            80: 
        !            81: 
        !            82: volatile ast_t need_ast[NCPUS];
        !            83: 
        !            84: void
        !            85: ast_init()
        !            86: {
        !            87: #ifndef        MACHINE_AST
        !            88:        register int i;
        !            89: 
        !            90:        for (i=0; i<NCPUS; i++)
        !            91:                need_ast[i] = 0;
        !            92: #endif MACHINE_AST
        !            93: }
        !            94: 
        !            95: #ifdef notdef
        !            96: void
        !            97: ast_taken()
        !            98: {
        !            99:        register thread_t self = current_thread();
        !           100:        register ast_t reasons;
        !           101: 
        !           102:        /*
        !           103:         *      Interrupts are still disabled.
        !           104:         *      We must clear need_ast and then enable interrupts.
        !           105:         */
        !           106: 
        !           107:        reasons = need_ast[cpu_number()];
        !           108:        need_ast[cpu_number()] = AST_ZILCH;
        !           109:        (void) spl0();
        !           110: 
        !           111:        /*
        !           112:         *      These actions must not block.
        !           113:         */
        !           114: 
        !           115:        if (reasons & AST_NETWORK)
        !           116:                net_ast();
        !           117: 
        !           118:        /*
        !           119:         *      Make darn sure that we don't call thread_halt_self
        !           120:         *      or thread_block from the idle thread.
        !           121:         */
        !           122: 
        !           123:        if (self != current_processor()->idle_thread) {
        !           124:                while (thread_should_halt(self))
        !           125:                        thread_halt_self();
        !           126: 
        !           127:                /*
        !           128:                 *      One of the previous actions might well have
        !           129:                 *      woken a high-priority thread, so we use
        !           130:                 *      csw_needed in addition to AST_BLOCK.
        !           131:                 */
        !           132: 
        !           133:                if ((reasons & AST_BLOCK) ||
        !           134:                    csw_needed(self, current_processor())) {
        !           135:                        counter(c_ast_taken_block++);
        !           136:                        thread_block_continue(thread_exception_return);
        !           137:                }
        !           138:        }
        !           139: }
        !           140: #endif
        !           141: 
        !           142: void
        !           143: ast_check()
        !           144: {
        !           145:        register struct proc    *p;
        !           146:        register int            mycpu = cpu_number();
        !           147:        register processor_t    myprocessor;
        !           148:        register thread_t       thread = current_thread();
        !           149:        register run_queue_t    rq;
        !           150:        spl_t                   s = splsched();
        !           151: 
        !           152:        /*
        !           153:         *      Check processor state for ast conditions.
        !           154:         */
        !           155:        myprocessor = cpu_to_processor(mycpu);
        !           156:        switch(myprocessor->state) {
        !           157:            case PROCESSOR_OFF_LINE:
        !           158:            case PROCESSOR_IDLE:
        !           159:            case PROCESSOR_DISPATCHING:
        !           160:                /*
        !           161:                 *      No ast.
        !           162:                 */
        !           163:                break;
        !           164: 
        !           165: #if    NCPUS > 1
        !           166:            case PROCESSOR_ASSIGN:
        !           167:            case PROCESSOR_SHUTDOWN:
        !           168:                /*
        !           169:                 *      Need ast to force action thread onto processor.
        !           170:                 *
        !           171:                 * XXX  Should check if action thread is already there.
        !           172:                 */
        !           173:                ast_on(mycpu, AST_BLOCK);
        !           174:                break;
        !           175: #endif NCPUS > 1
        !           176: 
        !           177:            case PROCESSOR_RUNNING:
        !           178: 
        !           179:                /*
        !           180:                 *      XXX Check for signals.
        !           181:                 */
        !           182:                p = thread->task->proc;
        !           183:                if (p) {
        !           184:                        if ((thread != THREAD_NULL && SHOULDissignal(p, thread->_uthread)))
        !           185:                                ast_on(mycpu, AST_UNIX);
        !           186:                }
        !           187: 
        !           188:                /*
        !           189:                 *      Propagate thread ast to processor.  If we already
        !           190:                 *      need an ast, don't look for more reasons.
        !           191:                 */
        !           192:                ast_propagate(thread, mycpu);
        !           193:                if (ast_needed(mycpu))
        !           194:                        break;
        !           195: 
        !           196:                /*
        !           197:                 *      Context switch check.  The csw_needed macro isn't
        !           198:                 *      used here because the rq->low hint may be wrong,
        !           199:                 *      and fixing it here avoids an extra ast.
        !           200:                 *      First check the easy cases.
        !           201:                 */
        !           202:                if (thread->state & TH_SUSP || myprocessor->runq.count > 0) {
        !           203:                        ast_on(mycpu, AST_BLOCK);
        !           204:                        break;
        !           205:                }
        !           206: 
        !           207:                /*
        !           208:                 *      Update lazy evaluated runq->low if only timesharing.
        !           209:                 */
        !           210: #if    MACH_FIXPRI
        !           211:                if (myprocessor->processor_set->policies & POLICY_FIXEDPRI) {
        !           212:                    if (csw_needed(thread,myprocessor)) {
        !           213:                        ast_on(mycpu, AST_BLOCK);
        !           214:                        break;
        !           215:                    }
        !           216:                    else {
        !           217:                        /*
        !           218:                         *      For fixed priority threads, set first_quantum
        !           219:                         *      so entire new quantum is used.
        !           220:                         */
        !           221:                        if (thread->policy == POLICY_FIXEDPRI)
        !           222:                            myprocessor->first_quantum = TRUE;
        !           223:                    }
        !           224:                }
        !           225:                else {
        !           226: #endif MACH_FIXPRI                     
        !           227:                rq = &(myprocessor->processor_set->runq);
        !           228:                if (!(myprocessor->first_quantum) && (rq->count > 0)) {
        !           229:                    register queue_t    q;
        !           230:                    /*
        !           231:                     *  This is not the first quantum, and there may
        !           232:                     *  be something in the processor_set runq.
        !           233:                     *  Check whether low hint is accurate.
        !           234:                     */
        !           235:                    q = rq->runq + *(volatile int *)&rq->high;
        !           236:                    if (queue_empty(q)) {
        !           237:                        register int i;
        !           238: 
        !           239:                        /*
        !           240:                         *      Need to recheck and possibly update hint.
        !           241:                         */
        !           242:                        simple_lock(&rq->lock);
        !           243:                        q = rq->runq + rq->high;
        !           244:                        if (rq->count > 0) {
        !           245:                            for (i = rq->high; i >= 0; i--) {
        !           246:                                if(!(queue_empty(q)))
        !           247:                                    break;
        !           248:                                q--;
        !           249:                            }
        !           250:                            rq->high = i;
        !           251:                        }
        !           252:                        simple_unlock(&rq->lock);
        !           253:                    }
        !           254: 
        !           255:                    if (rq->high >= thread->sched_pri) {
        !           256:                        ast_on(mycpu, AST_BLOCK);
        !           257:                        break;
        !           258:                    }
        !           259:                }
        !           260: #if    MACH_FIXPRI
        !           261:                }
        !           262: #endif MACH_FIXPRI
        !           263:                break;
        !           264: 
        !           265:            default:
        !           266:                panic("ast_check: Bad processor state");
        !           267:        }
        !           268: 
        !           269:        (void) splx(s);
        !           270: }

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