osfmk/kern/sched.h

   1 /*
   2  * Copyright (c) 2000 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  *      File:   sched.h
  54  *      Author: Avadis Tevanian, Jr.
  55  *      Date:   1985
  56  *
  57  *      Header file for scheduler.
  58  *
  59  */
  60
  61 #ifndef _KERN_SCHED_H_
  62 #define _KERN_SCHED_H_
  63
  64 #include <cpus.h>
  65 #include <simple_clock.h>
  66 #include <stat_time.h>
  67
  68 #include <mach/policy.h>
  69 #include <kern/kern_types.h>
  70 #include <kern/queue.h>
  71 #include <kern/lock.h>
  72 #include <kern/macro_help.h>
  73
  74 #if     STAT_TIME
  75
  76 /*
  77  *      Statistical timing uses microseconds as timer units.  16 bit shift
  78  *      yields priorities.  PRI_SHIFT_2 isn't needed.
  79  */
  80 #define PRI_SHIFT       (16 - SCHED_TICK_SHIFT)
  81
  82 #else   /* STAT_TIME */
  83
  84 /*
  85  *      Otherwise machine provides shift(s) based on time units it uses.
  86  */
  87 #include <machine/sched_param.h>
  88
  89 #endif  /* STAT_TIME */
  90
  91 #define NRQS            128                             /* 128 run queues per cpu */
  92 #define NRQBM           (NRQS / 32)             /* number of run queue bit maps */
  93
  94 #define MAXPRI          (NRQS-1)
  95 #define MINPRI          IDLEPRI                 /* lowest legal priority schedulable */
  96 #define IDLEPRI         0                               /* idle thread priority */
  97 #define DEPRESSPRI      MINPRI                  /* depress priority */
  98
  99 /*
 100  *      High-level priority assignments
 101  *
 102  *************************************************************************
 103  * 127          Reserved (real-time)
 104  *                              A
 105  *                              +
 106  *                      (32 levels)
 107  *                              +
 108  *                              V
 109  * 96           Reserved (real-time)
 110  * 95           Kernel mode only
 111  *                              A
 112  *                              +
 113  *                      (16 levels)
 114  *                              +
 115  *                              V
 116  * 80           Kernel mode only
 117  * 79           High priority
 118  *                              A
 119  *                              +
 120  *                      (16 levels)
 121  *                              +
 122  *                              V
 123  * 64           High priority
 124  * 63           Elevated priorities
 125  *                              A
 126  *                              +
 127  *                      (12 levels)
 128  *                              +
 129  *                              V
 130  * 52           Elevated priorities
 131  * 51           Elevated priorities (incl. BSD +nice)
 132  *                              A
 133  *                              +
 134  *                      (20 levels)
 135  *                              +
 136  *                              V
 137  * 32           Elevated priorities (incl. BSD +nice)
 138  * 31           Default (default base for threads)
 139  * 30           Lowered priorities (incl. BSD -nice)
 140  *                              A
 141  *                              +
 142  *                      (20 levels)
 143  *                              +
 144  *                              V
 145  * 11           Lowered priorities (incl. BSD -nice)
 146  * 10           Lowered priorities (aged pri's)
 147  *                              A
 148  *                              +
 149  *                      (11 levels)
 150  *                              +
 151  *                              V
 152  * 0            Lowered priorities (aged pri's / idle)
 153  *************************************************************************
 154  */
 155
 156 #define BASEPRI_REALTIME        (MAXPRI - (NRQS / 4) + 1)                       /* 96 */
 157
 158 #define MAXPRI_STANDARD         (BASEPRI_REALTIME - 1)                          /* 95 */
 159
 160 #define MAXPRI_KERNBAND         MAXPRI_STANDARD                                         /* 95 */
 161 #define MINPRI_KERNBAND         (MAXPRI_KERNBAND - (NRQS / 8) + 1)      /* 80 */
 162
 163 #define MAXPRI_HIGHBAND         (MINPRI_KERNBAND - 1)                           /* 79 */
 164 #define MINPRI_HIGHBAND         (MAXPRI_HIGHBAND - (NRQS / 8) + 1)      /* 64 */
 165
 166 #define MAXPRI_MAINBAND         (MINPRI_HIGHBAND - 1)                           /* 63 */
 167 #define BASEPRI_DEFAULT         (MAXPRI_MAINBAND - (NRQS / 4))          /* 31 */
 168 #define MINPRI_MAINBAND         MINPRI                                                          /*  0 */
 169
 170 #define MINPRI_STANDARD         MINPRI_MAINBAND                                         /*  0 */
 171
 172 /*
 173  *      Macro to check for invalid priorities.
 174  */
 175 #define invalid_pri(pri) ((pri) < MINPRI || (pri) > MAXPRI)
 176
 177 struct run_queue {
 178         queue_head_t            queues[NRQS];           /* one for each priority */
 179         decl_simple_lock_data(,lock)                    /* one lock for all queues */
 180         int                                     bitmap[NRQBM];          /* run queue bitmap array */
 181         int                                     highq;                          /* highest runnable queue */
 182         int                                     count;                          /* # of runnable threads */
 183 };
 184
 185 typedef struct run_queue        *run_queue_t;
 186 #define RUN_QUEUE_NULL          ((run_queue_t) 0)
 187
 188 #define csw_needed(thread, processor) (                                                                         \
 189         ((thread)->state & TH_SUSP)                                                                             ||              \
 190         ((processor)->first_quantum?                                                                                    \
 191          ((processor)->runq.highq > (thread)->sched_pri                         ||                      \
 192           (processor)->processor_set->runq.highq > (thread)->sched_pri) :               \
 193          ((processor)->runq.highq >= (thread)->sched_pri                        ||                      \
 194           (processor)->processor_set->runq.highq >= (thread)->sched_pri))       )
 195
 196 /*
 197  *      Scheduler routines.
 198  */
 199
 200 /* Remove thread from its run queue */
 201 extern run_queue_t      rem_runq(
 202                                         thread_t        thread);
 203
 204 /* Mach factor computation (in mach_factor.c) */
 205 extern void             compute_mach_factor(void);
 206
 207 /* Update threads quantum (in priority.c) */
 208 extern void             thread_quantum_update(
 209                                         int                     mycpu,
 210                                         thread_t        thread,
 211                                         int                     nticks,
 212                                         int                     state);
 213
 214 extern int              min_quantum;    /* defines max context switch rate */
 215
 216 /*
 217  *      Shift structures for holding update shifts.  Actual computation
 218  *      is  usage = (usage >> shift1) +/- (usage >> abs(shift2))  where the
 219  *      +/- is determined by the sign of shift 2.
 220  */
 221 struct shift {
 222         int     shift1;
 223         int     shift2;
 224 };
 225
 226 typedef struct shift    *shift_t, shift_data_t;
 227
 228 /*
 229  *      Age usage (1 << SCHED_TICK_SHIFT) times per second.
 230  */
 231
 232 extern unsigned sched_tick;
 233
 234 #define SCHED_TICK_SHIFT        3
 235
 236 #define SCHED_SCALE             128
 237 #define SCHED_SHIFT             7
 238
 239 /*
 240  *      thread_timer_delta macro takes care of both thread timers.
 241  */
 242
 243 #define thread_timer_delta(thread)                                              \
 244 MACRO_BEGIN                                                                                                     \
 245         register unsigned       delta;                                                          \
 246                                                                                                                         \
 247         delta = 0;                                                                                              \
 248         TIMER_DELTA((thread)->system_timer,                                             \
 249                                         (thread)->system_timer_save, delta);    \
 250         TIMER_DELTA((thread)->user_timer,                                               \
 251                                         (thread)->user_timer_save, delta);              \
 252         (thread)->cpu_delta += delta;                                                   \
 253         (thread)->sched_delta += (delta *                                               \
 254                                         (thread)->processor_set->sched_load);   \
 255 MACRO_END
 256
 257 #if     SIMPLE_CLOCK
 258 /*
 259  *      sched_usec is an exponential average of number of microseconds
 260  *      in a second for clock drift compensation.
 261  */
 262
 263 extern int      sched_usec;
 264 #endif  /* SIMPLE_CLOCK */
 265
 266 #endif  /* _KERN_SCHED_H_ */