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Annotation of kernel/kern/mach_factor.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:  *     File:   kern/mach_factor.c
        !            52:  *     Author: Avadis Tevanian, Jr.
        !            53:  *     Date:   1986
        !            54:  *
        !            55:  *     Compute the Mach Factor.
        !            56:  */
        !            57: 
        !            58: #include <cpus.h>
        !            59: 
        !            60: #include <mach/machine.h>
        !            61: #include <mach/processor_info.h>
        !            62: #include <kern/sched.h>
        !            63: #include <kern/processor.h>
        !            64: #include <kern/time_out.h>
        !            65: 
        !            66: long   avenrun[3] = {0, 0, 0};
        !            67: long   mach_factor[3] = {0, 0, 0};
        !            68: 
        !            69: /*
        !            70:  * Values are scaled by LOAD_SCALE, defined in processor_info.h
        !            71:  */
        !            72: static long    fract[3] = {
        !            73:        800,                    /* (4.0/5.0) 5 second average */
        !            74:        966,                    /* (29.0/30.0) 30 second average */
        !            75:        983,                    /* (59.0/60.) 1 minute average */
        !            76: };
        !            77: 
        !            78: void compute_mach_factor()
        !            79: {
        !            80:        register processor_set_t        pset;
        !            81:        register processor_t            processor;
        !            82:        register int            ncpus;
        !            83:        register int            nthreads;
        !            84:        register long           factor_now;
        !            85:        register long           average_now;
        !            86:        register long           load_now;
        !            87: 
        !            88:        simple_lock(&all_psets_lock);
        !            89:        pset = (processor_set_t) queue_first(&all_psets);
        !            90:        while (!queue_end(&all_psets, (queue_entry_t)pset)) {
        !            91: 
        !            92:            /*
        !            93:             *  If no processors, this pset is in suspended animation.
        !            94:             *  No load calculations are performed.
        !            95:             */
        !            96:            pset_lock(pset);
        !            97:            if((ncpus = pset->processor_count) > 0) {
        !            98: 
        !            99:                /*
        !           100:                 *      Count number of threads.
        !           101:                 */
        !           102:                nthreads = pset->runq.count;
        !           103:                processor = (processor_t) queue_first(&pset->processors);
        !           104:                while (!queue_end(&pset->processors,
        !           105:                    (queue_entry_t)processor)) {
        !           106:                        nthreads += processor->runq.count;
        !           107:                        processor =
        !           108:                            (processor_t) queue_next(&processor->processors);
        !           109:                }
        !           110: 
        !           111:                /*
        !           112:                 * account for threads on cpus.
        !           113:                 */
        !           114:                nthreads += ncpus - pset->idle_count; 
        !           115: 
        !           116:                /*
        !           117:                 *      The current thread (running this calculation)
        !           118:                 *      doesn't count; it's always in the default pset.
        !           119:                 */
        !           120:                if (pset == &default_pset)
        !           121:                   nthreads -= 1;
        !           122: 
        !           123:                if (nthreads > ncpus) {
        !           124:                        factor_now = (ncpus * LOAD_SCALE) / (nthreads + 1);
        !           125:                        load_now = (nthreads << SCHED_SHIFT) / ncpus;
        !           126:                }
        !           127:                else {
        !           128:                        factor_now = (ncpus - nthreads) * LOAD_SCALE;
        !           129:                        load_now = SCHED_SCALE;
        !           130:                }
        !           131: 
        !           132:                /*
        !           133:                 *      Load average and mach factor calculations for
        !           134:                 *      those that ask about these things.
        !           135:                 */
        !           136: 
        !           137:                average_now = nthreads * LOAD_SCALE;
        !           138: 
        !           139:                pset->mach_factor =
        !           140:                        ((pset->mach_factor << 2) + factor_now)/5;
        !           141:                pset->load_average =
        !           142:                        ((pset->load_average << 2) + average_now)/5;
        !           143: 
        !           144:                /*
        !           145:                 *      And some ugly stuff to keep w happy.
        !           146:                 */
        !           147:                if (pset == &default_pset) {
        !           148:                    register int i;
        !           149: 
        !           150:                    for (i = 0; i < 3; i++) {
        !           151:                        mach_factor[i] = ( (mach_factor[i]*fract[i])
        !           152:                                 + (factor_now*(LOAD_SCALE-fract[i])) )
        !           153:                                / LOAD_SCALE;
        !           154:                        avenrun[i] = ( (avenrun[i]*fract[i])
        !           155:                                 + (average_now*(LOAD_SCALE-fract[i])) )
        !           156:                                / LOAD_SCALE;
        !           157:                    }
        !           158:                }
        !           159: 
        !           160:                /*
        !           161:                 *      sched_load is the only thing used by scheduler.
        !           162:                 *      It is always at least 1 (i.e. SCHED_SCALE).
        !           163:                 */
        !           164:                pset->sched_load = (pset->sched_load + load_now) >> 1;
        !           165:            }
        !           166: 
        !           167:            pset_unlock(pset);
        !           168:            pset = (processor_set_t) queue_next(&pset->all_psets);
        !           169:        }
        !           170: 
        !           171:        simple_unlock(&all_psets_lock);
        !           172: }

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