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Annotation of kernel/kern/thread_swap.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:  *     File:   kern/thread_swap.c
        !            53:  *     Author: Avadis Tevanian, Jr.
        !            54:  *     Date:   1987
        !            55:  *
        !            56:  *     Mach thread swapper:
        !            57:  *             Find idle threads to swap, freeing up kernel stack resources
        !            58:  *             at the expense of allowing them to execute.
        !            59:  *
        !            60:  *             Swap in threads that need to be run.  This is done here
        !            61:  *             by the swapper thread since it cannot be done (in general)
        !            62:  *             when the kernel tries to place a thread on a run queue.
        !            63:  *
        !            64:  *     Note: The act of swapping a thread in Mach does not mean that
        !            65:  *     its memory gets forcibly swapped to secondary storage.  The memory
        !            66:  *     for the task corresponding to a swapped thread is paged out
        !            67:  *     through the normal paging mechanism.
        !            68:  *
        !            69:  */
        !            70: 
        !            71: #include <ipc/ipc_kmsg.h>
        !            72: #include <kern/counters.h>
        !            73: #include <kern/thread.h>
        !            74: #include <kern/lock.h>
        !            75: #include <vm/vm_map.h>
        !            76: #include <vm/vm_kern.h>
        !            77: #include <mach/vm_param.h>
        !            78: #include <kern/sched_prim.h>
        !            79: #include <kern/processor.h>
        !            80: #include <kern/thread_swap.h>
        !            81: #include <machine/machspl.h>           /* for splsched */
        !            82: 
        !            83: 
        !            84: 
        !            85: queue_head_t           swapin_queue;
        !            86: decl_simple_lock_data(,        swapper_lock_data)
        !            87: 
        !            88: #define swapper_lock()         simple_lock(&swapper_lock_data)
        !            89: #define swapper_unlock()       simple_unlock(&swapper_lock_data)
        !            90: 
        !            91: /*
        !            92:  *     swapper_init: [exported]
        !            93:  *
        !            94:  *     Initialize the swapper module.
        !            95:  */
        !            96: void swapper_init()
        !            97: {
        !            98:        queue_init(&swapin_queue);
        !            99:        simple_lock_init(&swapper_lock_data);
        !           100: }
        !           101: 
        !           102: /*
        !           103:  *     thread_swapin: [exported]
        !           104:  *
        !           105:  *     Place the specified thread in the list of threads to swapin.  It
        !           106:  *     is assumed that the thread is locked, therefore we are at splsched.
        !           107:  *
        !           108:  *     We don't bother with stack_alloc_try to optimize swapin;
        !           109:  *     our callers have already tried that route.
        !           110:  */
        !           111: 
        !           112: void thread_swapin(thread)
        !           113:        thread_t        thread;
        !           114: {
        !           115:        switch (thread->state & TH_SWAP_STATE) {
        !           116:            case TH_SWAPPED:
        !           117:                /*
        !           118:                 *      Swapped out - queue for swapin thread.
        !           119:                 */
        !           120:                thread->state = (thread->state & ~TH_SWAP_STATE)
        !           121:                                | TH_SW_COMING_IN;
        !           122:                swapper_lock();
        !           123:                enqueue_tail(&swapin_queue, (queue_entry_t) thread);
        !           124:                swapper_unlock();
        !           125:                thread_wakeup((event_t) &swapin_queue);
        !           126:                break;
        !           127: 
        !           128:            case TH_SW_COMING_IN:
        !           129:                /*
        !           130:                 *      Already queued for swapin thread, or being
        !           131:                 *      swapped in.
        !           132:                 */
        !           133:                break;
        !           134: 
        !           135:            default:
        !           136:                /*
        !           137:                 *      Already swapped in.
        !           138:                 */
        !           139:                panic("thread_swapin");
        !           140:        }
        !           141: }
        !           142: 
        !           143: /*
        !           144:  *     thread_doswapin:
        !           145:  *
        !           146:  *     Swapin the specified thread, if it should be runnable, then put
        !           147:  *     it on a run queue.  No locks should be held on entry, as it is
        !           148:  *     likely that this routine will sleep (waiting for stack allocation).
        !           149:  */
        !           150: void thread_doswapin(thread)
        !           151:        register thread_t thread;
        !           152: {
        !           153:        spl_t   s;
        !           154: 
        !           155:        /*
        !           156:         *      Allocate the kernel stack.
        !           157:         */
        !           158: 
        !           159:        stack_alloc(thread, thread_continue);
        !           160: 
        !           161:        /*
        !           162:         *      Place on run queue.  
        !           163:         */
        !           164: 
        !           165:        s = splsched();
        !           166:        thread_lock(thread);
        !           167:        thread->state &= ~(TH_SWAPPED | TH_SW_COMING_IN);
        !           168:        if (thread->state & TH_RUN)
        !           169:                thread_setrun(thread, TRUE);
        !           170:        thread_unlock(thread);
        !           171:        (void) splx(s);
        !           172: }
        !           173: 
        !           174: /*
        !           175:  *     swapin_thread: [exported]
        !           176:  *
        !           177:  *     This procedure executes as a kernel thread.  Threads that need to
        !           178:  *     be swapped in are swapped in by this thread.
        !           179:  */
        !           180: void swapin_thread_continue()
        !           181: {
        !           182:        for (;;) {
        !           183:                register thread_t thread;
        !           184:                spl_t s;
        !           185: 
        !           186:                s = splsched();
        !           187:                swapper_lock();
        !           188: 
        !           189:                while ((thread = (thread_t) dequeue_head(&swapin_queue))
        !           190:                                                        != THREAD_NULL) {
        !           191:                        swapper_unlock();
        !           192:                        (void) splx(s);
        !           193: 
        !           194:                        thread_doswapin(thread);                /* may block */
        !           195: 
        !           196:                        s = splsched();
        !           197:                        swapper_lock();
        !           198:                }
        !           199: 
        !           200:                assert_wait((event_t) &swapin_queue, FALSE);
        !           201:                swapper_unlock();
        !           202:                (void) splx(s);
        !           203:                counter(c_swapin_thread_block++);
        !           204:                thread_block_with_continuation(swapin_thread_continue);
        !           205:        }
        !           206: }
        !           207: 
        !           208: void swapin_thread()
        !           209: {
        !           210:        stack_privilege(current_thread());
        !           211:        current_thread()->vm_privilege = TRUE;
        !           212: 
        !           213:        swapin_thread_continue();
        !           214:        /*NOTREACHED*/
        !           215: }

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