osfmk/kern/priority.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * @OSF_COPYRIGHT@
  27  */
  28 /*
  29  * Mach Operating System
  30  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  31  * All Rights Reserved.
  32  *
  33  * Permission to use, copy, modify and distribute this software and its
  34  * documentation is hereby granted, provided that both the copyright
  35  * notice and this permission notice appear in all copies of the
  36  * software, derivative works or modified versions, and any portions
  37  * thereof, and that both notices appear in supporting documentation.
  38  *
  39  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  40  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  41  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  42  *
  43  * Carnegie Mellon requests users of this software to return to
  44  *
  45  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  46  *  School of Computer Science
  47  *  Carnegie Mellon University
  48  *  Pittsburgh PA 15213-3890
  49  *
  50  * any improvements or extensions that they make and grant Carnegie Mellon
  51  * the rights to redistribute these changes.
  52  */
  53 /*
  54  */
  55 /*
  56  *      File:   clock_prim.c
  57  *      Author: Avadis Tevanian, Jr.
  58  *      Date:   1986
  59  *
  60  *      Clock primitives.
  61  */
  62
  63 #include <cpus.h>
  64
  65 #include <mach/boolean.h>
  66 #include <mach/kern_return.h>
  67 #include <mach/machine.h>
  68 #include <kern/host.h>
  69 #include <kern/mach_param.h>
  70 #include <kern/sched.h>
  71 #include <kern/spl.h>
  72 #include <kern/thread.h>
  73 #include <kern/processor.h>
  74 #include <machine/machparam.h>
  75
  76 /*
  77  *      thread_quantum_expire:
  78  *
  79  *      Recalculate the quantum and priority for a thread.
  80  */
  81
  82 void
  83 thread_quantum_expire(
  84         timer_call_param_t      p0,
  85         timer_call_param_t      p1)
  86 {
  87         register processor_t            myprocessor = p0;
  88         register thread_t                       thread = p1;
  89         spl_t                                           s;
  90
  91         s = splsched();
  92         thread_lock(thread);
  93
  94         /*
  95          *      Check for fail-safe trip.
  96          */
  97         if (!(thread->sched_mode & TH_MODE_TIMESHARE)) {
  98                 extern uint64_t         max_unsafe_computation;
  99                 uint64_t                        new_computation;
 100
 101                 new_computation = myprocessor->quantum_end;
 102                 new_computation -= thread->computation_epoch;
 103                 if (new_computation + thread->computation_metered >
 104                                                                                         max_unsafe_computation) {
 105                         extern uint32_t         sched_safe_duration;
 106
 107                         if (thread->sched_mode & TH_MODE_REALTIME) {
 108                                 thread->priority = DEPRESSPRI;
 109
 110                                 thread->safe_mode |= TH_MODE_REALTIME;
 111                                 thread->sched_mode &= ~TH_MODE_REALTIME;
 112                         }
 113
 114                         pset_share_incr(thread->processor_set);
 115
 116                         thread->safe_release = sched_tick + sched_safe_duration;
 117                         thread->sched_mode |= (TH_MODE_FAILSAFE|TH_MODE_TIMESHARE);
 118                         thread->sched_mode &= ~TH_MODE_PREEMPT;
 119                 }
 120         }
 121
 122         /*
 123          *      Recompute scheduled priority if appropriate.
 124          */
 125         if (thread->sched_stamp != sched_tick)
 126                 update_priority(thread);
 127         else
 128         if (thread->sched_mode & TH_MODE_TIMESHARE) {
 129                 thread_timer_delta(thread);
 130                 thread->sched_usage += thread->sched_delta;
 131                 thread->sched_delta = 0;
 132
 133                 /*
 134                  * Adjust the scheduled priority if
 135                  * the thread has not been promoted
 136                  * and is not depressed.
 137                  */
 138                 if (    !(thread->sched_mode & TH_MODE_PROMOTED)        &&
 139                                 !(thread->sched_mode & TH_MODE_ISDEPRESSED)             )
 140                         compute_my_priority(thread);
 141         }
 142
 143         /*
 144          *      This quantum is up, give this thread another.
 145          */
 146         if (first_timeslice(myprocessor))
 147                 myprocessor->timeslice--;
 148
 149         thread_quantum_init(thread);
 150         myprocessor->quantum_end += thread->current_quantum;
 151         timer_call_enter1(&myprocessor->quantum_timer,
 152                                                         thread, myprocessor->quantum_end);
 153
 154         thread_unlock(thread);
 155
 156         /*
 157          * Check for and schedule ast if needed.
 158          */
 159         ast_check(myprocessor);
 160
 161         splx(s);
 162 }