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1.1 root 1: /*
2: * Mach Operating System
3: * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
4: * All Rights Reserved.
5: *
6: * Permission to use, copy, modify and distribute this software and its
7: * documentation is hereby granted, provided that both the copyright
8: * notice and this permission notice appear in all copies of the
9: * software, derivative works or modified versions, and any portions
10: * thereof, and that both notices appear in supporting documentation.
11: *
12: * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
13: * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
14: * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
15: *
16: * Carnegie Mellon requests users of this software to return to
17: *
18: * Software Distribution Coordinator or [email protected]
19: * School of Computer Science
20: * Carnegie Mellon University
21: * Pittsburgh PA 15213-3890
22: *
23: * any improvements or extensions that they make and grant Carnegie Mellon
24: * the rights to redistribute these changes.
25: */
26: /*
27: * File: sched.h
28: * Author: Avadis Tevanian, Jr.
29: * Date: 1985
30: *
31: * Header file for scheduler.
32: *
33: */
34:
35: #ifndef _KERN_SCHED_H_
36: #define _KERN_SCHED_H_
37:
38: #include <cpus.h>
39: #include <mach_fixpri.h>
40: #include <simple_clock.h>
41: #include <stat_time.h>
42:
43: #include <kern/queue.h>
44: #include <kern/lock.h>
45: #include <kern/macro_help.h>
46:
47: #if MACH_FIXPRI
48: #include <mach/policy.h>
49: #endif /* MACH_FIXPRI */
50:
51: #if STAT_TIME
52:
53: /*
54: * Statistical timing uses microseconds as timer units. 18 bit shift
55: * yields priorities. PRI_SHIFT_2 isn't needed.
56: */
57: #define PRI_SHIFT 18
58:
59: #else /* STAT_TIME */
60:
61: /*
62: * Otherwise machine provides shift(s) based on time units it uses.
63: */
64: #include <machine/sched_param.h>
65:
66: #endif /* STAT_TIME */
67: #define NRQS 32 /* 32 run queues per cpu */
68:
69: struct run_queue {
70: queue_head_t runq[NRQS]; /* one for each priority */
71: decl_simple_lock_data(, lock) /* one lock for all queues */
72: int low; /* low queue value */
73: int count; /* count of threads runable */
74: };
75:
76: typedef struct run_queue *run_queue_t;
77: #define RUN_QUEUE_NULL ((run_queue_t) 0)
78:
79: #if MACH_FIXPRI
80: /*
81: * NOTE: For fixed priority threads, first_quantum indicates
82: * whether context switch at same priority is ok. For timeshareing
83: * it indicates whether preempt is ok.
84: */
85:
86: #define csw_needed(thread, processor) ((thread)->state & TH_SUSP || \
87: ((processor)->runq.count > 0) || \
88: ((thread)->policy == POLICY_TIMESHARE && \
89: (processor)->first_quantum == FALSE && \
90: (processor)->processor_set->runq.count > 0 && \
91: (processor)->processor_set->runq.low <= \
92: (thread)->sched_pri) || \
93: ((thread)->policy == POLICY_FIXEDPRI && \
94: (processor)->processor_set->runq.count > 0 && \
95: ((((processor)->first_quantum == FALSE) && \
96: ((processor)->processor_set->runq.low <= \
97: (thread)->sched_pri)) || \
98: ((processor)->processor_set->runq.low < \
99: (thread)->sched_pri))))
100:
101: #else /* MACH_FIXPRI */
102: #define csw_needed(thread, processor) ((thread)->state & TH_SUSP || \
103: ((processor)->runq.count > 0) || \
104: ((processor)->first_quantum == FALSE && \
105: ((processor)->processor_set->runq.count > 0 && \
106: (processor)->processor_set->runq.low <= \
107: ((thread)->sched_pri))))
108: #endif /* MACH_FIXPRI */
109:
110: /*
111: * Scheduler routines.
112: */
113:
114: extern struct run_queue *rem_runq();
115: extern struct thread *choose_thread();
116: extern queue_head_t action_queue; /* assign/shutdown queue */
117: decl_simple_lock_data(extern,action_lock);
118:
119: extern int min_quantum; /* defines max context switch rate */
120:
121: /*
122: * Default base priorities for threads.
123: */
124: #define BASEPRI_SYSTEM 6
125: #define BASEPRI_USER 12
126:
127: /*
128: * Macro to check for invalid priorities.
129: */
130:
131: #define invalid_pri(pri) (((pri) < 0) || ((pri) >= NRQS))
132:
133: /*
134: * Shift structures for holding update shifts. Actual computation
135: * is usage = (usage >> shift1) +/- (usage >> abs(shift2)) where the
136: * +/- is determined by the sign of shift 2.
137: */
138: struct shift {
139: int shift1;
140: int shift2;
141: };
142:
143: typedef struct shift *shift_t, shift_data_t;
144:
145: /*
146: * sched_tick increments once a second. Used to age priorities.
147: */
148:
149: extern unsigned sched_tick;
150:
151: #define SCHED_SCALE 128
152: #define SCHED_SHIFT 7
153:
154: /*
155: * thread_timer_delta macro takes care of both thread timers.
156: */
157:
158: #define thread_timer_delta(thread) \
159: MACRO_BEGIN \
160: register unsigned delta; \
161: \
162: delta = 0; \
163: TIMER_DELTA((thread)->system_timer, \
164: (thread)->system_timer_save, delta); \
165: TIMER_DELTA((thread)->user_timer, \
166: (thread)->user_timer_save, delta); \
167: (thread)->cpu_delta += delta; \
168: (thread)->sched_delta += delta * \
169: (thread)->processor_set->sched_load; \
170: MACRO_END
171:
172: #if SIMPLE_CLOCK
173: /*
174: * sched_usec is an exponential average of number of microseconds
175: * in a second for clock drift compensation.
176: */
177:
178: extern int sched_usec;
179: #endif /* SIMPLE_CLOCK */
180:
181: #endif /* _KERN_SCHED_H_ */
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