osfmk/kern/priority.c

   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:   clock_prim.c
  54  *      Author: Avadis Tevanian, Jr.
  55  *      Date:   1986
  56  *
  57  *      Clock primitives.
  58  */
  59
  60 #include <cpus.h>
  61
  62 #include <mach/boolean.h>
  63 #include <mach/kern_return.h>
  64 #include <mach/machine.h>
  65 #include <kern/host.h>
  66 #include <kern/mach_param.h>
  67 #include <kern/sched.h>
  68 #include <kern/spl.h>
  69 #include <kern/thread.h>
  70 #include <kern/processor.h>
  71 #include <machine/machparam.h>
  72
  73 /*
  74  *      thread_quantum_expire:
  75  *
  76  *      Recalculate the quantum and priority for a thread.
  77  */
  78
  79 void
  80 thread_quantum_expire(
  81         timer_call_param_t      p0,
  82         timer_call_param_t      p1)
  83 {
  84         register processor_t            myprocessor = p0;
  85         register thread_t                       thread = p1;
  86         spl_t                                           s;
  87
  88         s = splsched();
  89         thread_lock(thread);
  90
  91         /*
  92          *      Check for fail-safe trip.
  93          */
  94         if (!(thread->sched_mode & TH_MODE_TIMESHARE)) {
  95                 extern uint64_t         max_unsafe_computation;
  96                 uint64_t                        new_computation;
  97
  98                 new_computation = myprocessor->quantum_end;
  99                 new_computation -= thread->computation_epoch;
 100                 if (new_computation + thread->computation_metered >
 101                                                                                         max_unsafe_computation) {
 102                         extern uint32_t         sched_safe_duration;
 103
 104                         if (thread->sched_mode & TH_MODE_REALTIME) {
 105                                 thread->priority = DEPRESSPRI;
 106
 107                                 thread->safe_mode |= TH_MODE_REALTIME;
 108                                 thread->sched_mode &= ~TH_MODE_REALTIME;
 109                         }
 110
 111                         thread->safe_release = sched_tick + sched_safe_duration;
 112                         thread->sched_mode |= (TH_MODE_FAILSAFE|TH_MODE_TIMESHARE);
 113                         thread->sched_mode &= ~TH_MODE_PREEMPT;
 114                 }
 115         }
 116
 117         /*
 118          *      Recompute scheduled priority if appropriate.
 119          */
 120         if (thread->sched_stamp != sched_tick)
 121                 update_priority(thread);
 122         else
 123         if (thread->sched_mode & TH_MODE_TIMESHARE) {
 124                 thread_timer_delta(thread);
 125                 thread->sched_usage += thread->sched_delta;
 126                 thread->sched_delta = 0;
 127
 128                 /*
 129                  * Adjust the scheduled priority if
 130                  * the thread has not been promoted
 131                  * and is not depressed.
 132                  */
 133                 if (    !(thread->sched_mode & TH_MODE_PROMOTED)        &&
 134                                 !(thread->sched_mode & TH_MODE_ISDEPRESSED)             )
 135                         compute_my_priority(thread);
 136         }
 137
 138         /*
 139          *      This quantum is up, give this thread another.
 140          */
 141         if (first_quantum(myprocessor))
 142                 myprocessor->slice_quanta--;
 143
 144         thread->current_quantum = (thread->sched_mode & TH_MODE_REALTIME)?
 145                                                                         thread->realtime.computation: std_quantum;
 146         myprocessor->quantum_end += thread->current_quantum;
 147         timer_call_enter1(&myprocessor->quantum_timer,
 148                                                         thread, myprocessor->quantum_end);
 149
 150         thread_unlock(thread);
 151
 152         /*
 153          * Check for and schedule ast if needed.
 154          */
 155         ast_check(myprocessor);
 156
 157         splx(s);
 158 }