osfmk/kern/sched_average.c

   1 /*
   2  * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * @OSF_COPYRIGHT@
  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  Software.Distribution@CS.CMU.EDU
  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 /*
  53  *      Author: Avadis Tevanian, Jr.
  54  *      Date:   1986
  55  *
  56  *      Compute various averages.
  57  */
  58
  59 #include <mach/mach_types.h>
  60
  61 #include <kern/sched.h>
  62 #include <kern/assert.h>
  63 #include <kern/processor.h>
  64 #include <kern/thread.h>
  65
  66 uint32_t        avenrun[3] = {0, 0, 0};
  67 uint32_t        mach_factor[3] = {0, 0, 0};
  68
  69 /*
  70  * Values are scaled by LOAD_SCALE, defined in processor_info.h
  71  */
  72 #define base(n)         ((n) << SCHED_TICK_SHIFT)
  73 #define frac(n)         (((base(n) - 1) * LOAD_SCALE) / base(n))
  74
  75 static uint32_t         fract[3] = {
  76         frac(5),                /* 5 second average */
  77         frac(30),               /* 30 second average */
  78         frac(60),               /* 1 minute average */
  79 };
  80
  81 #undef base
  82 #undef frac
  83
  84 static unsigned int             sched_nrun;
  85
  86 typedef void    (*sched_avg_comp_t)(
  87                                         void                    *param);
  88
  89 #define SCHED_AVG_SECS(n)       ((n) << SCHED_TICK_SHIFT)
  90
  91 static struct sched_average {
  92         sched_avg_comp_t        comp;
  93         void                            *param;
  94         int                                     period;
  95         int                                     tick;
  96 } sched_average[] = {
  97         { compute_averunnable, &sched_nrun, SCHED_AVG_SECS(5), 0 },
  98         { compute_stack_target, NULL, SCHED_AVG_SECS(5), 1 },
  99         { NULL, NULL, 0, 0 }
 100 };
 101
 102 typedef struct sched_average    *sched_average_t;
 103
 104 void
 105 compute_averages(void)
 106 {
 107         register processor_set_t        pset = &default_pset;
 108         register int                            ncpus;
 109         register int                            nthreads, nshared;
 110         sched_average_t                         avg;
 111         register uint32_t                       factor_now = 0;
 112         register uint32_t                       average_now = 0;
 113         register uint32_t                       load_now = 0;
 114
 115         if ((ncpus = pset->processor_count) > 0) {
 116                 /*
 117                  *      Retrieve counts, ignoring
 118                  *      the current thread.
 119                  */
 120                 nthreads = pset->run_count - 1;
 121                 nshared = pset->share_count;
 122
 123                 /*
 124                  *      Load average and mach factor calculations for
 125                  *      those which ask about these things.
 126                  */
 127                 average_now = nthreads * LOAD_SCALE;
 128
 129                 if (nthreads > ncpus)
 130                         factor_now = (ncpus * LOAD_SCALE) / (nthreads + 1);
 131                 else
 132                         factor_now = (ncpus - nthreads) * LOAD_SCALE;
 133
 134                 pset->mach_factor =     ((pset->mach_factor << 2) + factor_now) / 5;
 135                 pset->load_average = ((pset->load_average << 2) + average_now) / 5;
 136
 137                 /*
 138                  *      Compute the timeshare priority
 139                  *      conversion factor based on loading.
 140                  */
 141                 if (nshared > nthreads)
 142                         nshared = nthreads;
 143
 144                 if (nshared > ncpus) {
 145                         if (ncpus > 1)
 146                                 load_now = nshared / ncpus;
 147                         else
 148                                 load_now = nshared;
 149
 150                         if (load_now > NRQS - 1)
 151                                 load_now = NRQS - 1;
 152                 }
 153
 154                 /*
 155                  *      The conversion factor consists of
 156                  *      two components: a fixed value based
 157                  *      on the absolute time unit, and a
 158                  *      dynamic portion based on loading.
 159                  *
 160                  *      Zero loading results in a out of range
 161                  *      shift count.  Accumulated usage is ignored
 162                  *      during conversion and new usage deltas
 163                  *      are discarded.
 164                  */
 165                 pset->pri_shift = sched_pri_shift - sched_load_shifts[load_now];
 166         }
 167         else {
 168                 pset->mach_factor = pset->load_average = 0;
 169                 pset->pri_shift = INT8_MAX;
 170                 nthreads = pset->run_count;
 171         }
 172
 173         /*
 174          *      Sample total running threads.
 175          */
 176         sched_nrun = nthreads;
 177
 178         /*
 179          * Compute old-style Mach load averages.
 180          */
 181         {
 182                 register int            i;
 183
 184                 for (i = 0; i < 3; i++) {
 185                         mach_factor[i] = ((mach_factor[i] * fract[i]) +
 186                                                 (factor_now * (LOAD_SCALE - fract[i]))) / LOAD_SCALE;
 187
 188                         avenrun[i] = ((avenrun[i] * fract[i]) +
 189                                                 (average_now * (LOAD_SCALE - fract[i]))) / LOAD_SCALE;
 190                 }
 191         }
 192
 193         /*
 194          *      Compute averages in other components.
 195          */
 196         for (avg = sched_average; avg->comp != NULL; ++avg) {
 197                 if (++avg->tick >= avg->period) {
 198                         (*avg->comp)(avg->param);
 199                         avg->tick = 0;
 200                 }
 201         }
 202 }