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/*
* Mach Operating System
* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
* File: sched.h
* Author: Avadis Tevanian, Jr.
* Date: 1985
*
* Header file for scheduler.
*
*/
#ifndef _KERN_SCHED_H_
#define _KERN_SCHED_H_
#include <kern/queue.h>
#include <kern/lock.h>
#include <kern/kern_types.h>
#include <kern/macros.h>
#if MACH_FIXPRI
#include <mach/policy.h>
#endif /* MACH_FIXPRI */
#if STAT_TIME
/*
* Statistical timing uses microseconds as timer units. 18 bit shift
* yields priorities. PRI_SHIFT_2 isn't needed.
*/
#define PRI_SHIFT 18
#else /* STAT_TIME */
/*
* Otherwise machine provides shift(s) based on time units it uses.
*/
#include <machine/sched_param.h>
#endif /* STAT_TIME */
#define NRQS 50 /* 50 run queues per cpu */
struct run_queue {
queue_head_t runq[NRQS]; /* one for each priority */
decl_simple_lock_data(, lock) /* one lock for all queues */
int low; /* low queue value */
int count; /* count of threads runable */
};
typedef struct run_queue *run_queue_t;
#define RUN_QUEUE_NULL ((run_queue_t) 0)
#if MACH_FIXPRI
/*
* NOTE: For fixed priority threads, first_quantum indicates
* whether context switch at same priority is ok. For timeshareing
* it indicates whether preempt is ok.
*/
#define csw_needed(thread, processor) ((thread)->state & TH_SUSP || \
((processor)->runq.count > 0) || \
((thread)->policy == POLICY_TIMESHARE && \
(processor)->first_quantum == FALSE && \
(processor)->processor_set->runq.count > 0 && \
(processor)->processor_set->runq.low <= \
(thread)->sched_pri) || \
((thread)->policy == POLICY_FIXEDPRI && \
(processor)->processor_set->runq.count > 0 && \
((((processor)->first_quantum == FALSE) && \
((processor)->processor_set->runq.low <= \
(thread)->sched_pri)) || \
((processor)->processor_set->runq.low < \
(thread)->sched_pri))))
#else /* MACH_FIXPRI */
#define csw_needed(thread, processor) ((thread)->state & TH_SUSP || \
((processor)->runq.count > 0) || \
((processor)->first_quantum == FALSE && \
((processor)->processor_set->runq.count > 0 && \
(processor)->processor_set->runq.low <= \
((thread)->sched_pri))))
#endif /* MACH_FIXPRI */
/*
* Scheduler routines.
*/
extern struct run_queue *rem_runq(thread_t);
extern struct thread *choose_thread(processor_t);
extern queue_head_t action_queue; /* assign/shutdown queue */
decl_simple_lock_data(extern,action_lock);
extern int min_quantum; /* defines max context switch rate */
/*
* Default base priorities for threads.
*/
#define BASEPRI_SYSTEM 6
#define BASEPRI_USER 25
/*
* Macro to check for invalid priorities.
*/
#define invalid_pri(pri) (((pri) < 0) || ((pri) >= NRQS))
/*
* Shift structures for holding update shifts. Actual computation
* is usage = (usage >> shift1) +/- (usage >> abs(shift2)) where the
* +/- is determined by the sign of shift 2.
*/
struct shift {
int shift1;
int shift2;
};
typedef struct shift *shift_t, shift_data_t;
/*
* sched_tick increments once a second. Used to age priorities.
*/
extern unsigned sched_tick;
#define SCHED_SCALE 128
#define SCHED_SHIFT 7
/*
* thread_timer_delta macro takes care of both thread timers.
*/
#define thread_timer_delta(thread) \
MACRO_BEGIN \
unsigned delta; \
\
delta = 0; \
TIMER_DELTA((thread)->system_timer, \
(thread)->system_timer_save, delta); \
TIMER_DELTA((thread)->user_timer, \
(thread)->user_timer_save, delta); \
(thread)->cpu_delta += delta; \
(thread)->sched_delta += delta * \
(thread)->processor_set->sched_load; \
MACRO_END
#if SIMPLE_CLOCK
/*
* sched_usec is an exponential average of number of microseconds
* in a second for clock drift compensation.
*/
extern int sched_usec;
#endif /* SIMPLE_CLOCK */
#endif /* _KERN_SCHED_H_ */
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