osfmk/kern/sched_average.c

   1 /*
   2  * Copyright (c) 2000-2007 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
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  23  * Please see the License for the specific language governing rights and
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  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * Mach Operating System
  33  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  34  * All Rights Reserved.
  35  *
  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
  38  * notice and this permission notice appear in all copies of the
  39  * software, derivative works or modified versions, and any portions
  40  * thereof, and that both notices appear in supporting documentation.
  41  *
  42  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  43  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
  46  * Carnegie Mellon requests users of this software to return to
  47  *
  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
  50  *  Carnegie Mellon University
  51  *  Pittsburgh PA 15213-3890
  52  *
  53  * any improvements or extensions that they make and grant Carnegie Mellon
  54  * the rights to redistribute these changes.
  55  */
  56 /*
  57  */
  58 /*
  59  *      Author: Avadis Tevanian, Jr.
  60  *      Date:   1986
  61  *
  62  *      Compute various averages.
  63  */
  64
  65 #include <mach/mach_types.h>
  66
  67 #include <kern/sched.h>
  68 #include <kern/assert.h>
  69 #include <kern/processor.h>
  70 #include <kern/thread.h>
  71
  72 uint32_t        avenrun[3] = {0, 0, 0};
  73 uint32_t        mach_factor[3] = {0, 0, 0};
  74
  75 /*
  76  * Values are scaled by LOAD_SCALE, defined in processor_info.h
  77  */
  78 #define base(n)         ((n) << SCHED_TICK_SHIFT)
  79 #define frac(n)         (((base(n) - 1) * LOAD_SCALE) / base(n))
  80
  81 static uint32_t         fract[3] = {
  82         frac(5),                /* 5 second average */
  83         frac(30),               /* 30 second average */
  84         frac(60),               /* 1 minute average */
  85 };
  86
  87 #undef base
  88 #undef frac
  89
  90 static unsigned int             sched_nrun;
  91
  92 typedef void    (*sched_avg_comp_t)(
  93                                         void                    *param);
  94
  95 #define SCHED_AVG_SECS(n)       ((n) << SCHED_TICK_SHIFT)
  96
  97 static struct sched_average {
  98         sched_avg_comp_t        comp;
  99         void                            *param;
 100         int                                     period;
 101         int                                     tick;
 102 } sched_average[] = {
 103         { compute_averunnable, &sched_nrun, SCHED_AVG_SECS(5), 0 },
 104         { compute_stack_target, NULL, SCHED_AVG_SECS(5), 1 },
 105         { compute_memory_pressure, NULL, SCHED_AVG_SECS(1), 0 },
 106         { NULL, NULL, 0, 0 }
 107 };
 108
 109 typedef struct sched_average    *sched_average_t;
 110
 111 void
 112 compute_averages(void)
 113 {
 114         int                                     ncpus, nthreads, nshared;
 115         uint32_t                        factor_now, average_now, load_now = 0;
 116         sched_average_t         avg;
 117
 118         /*
 119          *      Retrieve counts, ignoring
 120          *      the current thread.
 121          */
 122         ncpus = processor_avail_count;
 123         nthreads = sched_run_count - 1;
 124         nshared = sched_share_count;
 125
 126         /*
 127          *      Load average and mach factor calculations for
 128          *      those which ask about these things.
 129          */
 130         average_now = nthreads * LOAD_SCALE;
 131
 132         if (nthreads > ncpus)
 133                 factor_now = (ncpus * LOAD_SCALE) / (nthreads + 1);
 134         else
 135                 factor_now = (ncpus - nthreads) * LOAD_SCALE;
 136
 137         sched_mach_factor =     ((sched_mach_factor << 2) + factor_now) / 5;
 138         sched_load_average = ((sched_load_average << 2) + average_now) / 5;
 139
 140         /*
 141          *      Compute the timeshare priority
 142          *      conversion factor based on loading.
 143          */
 144         if (nshared > nthreads)
 145                 nshared = nthreads;
 146
 147         if (nshared > ncpus) {
 148                 if (ncpus > 1)
 149                         load_now = nshared / ncpus;
 150                 else
 151                         load_now = nshared;
 152
 153                 if (load_now > NRQS - 1)
 154                         load_now = NRQS - 1;
 155         }
 156
 157         /*
 158          *      The conversion factor consists of
 159          *      two components: a fixed value based
 160          *      on the absolute time unit, and a
 161          *      dynamic portion based on loading.
 162          *
 163          *      Zero loading results in a out of range
 164          *      shift count.  Accumulated usage is ignored
 165          *      during conversion and new usage deltas
 166          *      are discarded.
 167          */
 168         sched_pri_shift = sched_fixed_shift - sched_load_shifts[load_now];
 169
 170         /*
 171          *      Sample total running threads.
 172          */
 173         sched_nrun = nthreads;
 174
 175         /*
 176          * Compute old-style Mach load averages.
 177          */
 178         {
 179                 register int            i;
 180
 181                 for (i = 0; i < 3; i++) {
 182                         mach_factor[i] = ((mach_factor[i] * fract[i]) +
 183                                                 (factor_now * (LOAD_SCALE - fract[i]))) / LOAD_SCALE;
 184
 185                         avenrun[i] = ((avenrun[i] * fract[i]) +
 186                                                 (average_now * (LOAD_SCALE - fract[i]))) / LOAD_SCALE;
 187                 }
 188         }
 189
 190         /*
 191          *      Compute averages in other components.
 192          */
 193         for (avg = sched_average; avg->comp != NULL; ++avg) {
 194                 if (++avg->tick >= avg->period) {
 195                         (*avg->comp)(avg->param);
 196                         avg->tick = 0;
 197                 }
 198         }
 199 }