Source to osfmk/kern/sched.h

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/*
 * @OSF_COPYRIGHT@
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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  [email protected]
 *  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 <cpus.h>
#include <simple_clock.h>
#include <stat_time.h>

#include <mach/policy.h>
#include <kern/kern_types.h>
#include <kern/queue.h>
#include <kern/lock.h>
#include <kern/macro_help.h>

#if	STAT_TIME

/*
 *	Statistical timing uses microseconds as timer units.  15 bit shift
 *	yields priorities.  PRI_SHIFT_2 isn't needed.
 */
#define PRI_SHIFT	15

#else	/* STAT_TIME */

/*
 *	Otherwise machine provides shift(s) based on time units it uses.
 */
#include <machine/sched_param.h>

#endif	/* STAT_TIME */

#define	NRQS		128				/* 128 run queues per cpu */
#define NRQBM		(NRQS / 32)		/* number of run queue bit maps */

#define MAXPRI		(NRQS-1)
#define LPRI		(IDLEPRI+2)		/* lowest pri reachable w/o depress */
#define MINPRI		(IDLEPRI+1)		/* lowest legal priority schedulable */
#define	IDLEPRI		0				/* idle thread priority */
#define DEPRESSPRI	MINPRI			/* depress priority */

/*
 *	Default base priorities for threads.
 */
#define	BASEPRI_KERNEL		MAXPRI
#define BASEPRI_SYSTEM		(BASEPRI_KERNEL - (NRQS / 4))
#define BASEPRI_SERVER		(BASEPRI_SYSTEM - (NRQS / 8))
#define BASEPRI_USER		(BASEPRI_SERVER - (NRQS / 8))

/*
 *	Macro to check for invalid priorities.
 */
#define invalid_pri(pri) ((pri) < MINPRI || (pri) > MAXPRI)

struct run_queue {
	queue_head_t		runq[NRQS];			/* one for each priority */
	decl_simple_lock_data(,lock)			/* one lock for all queues */
	int					bitmap[NRQBM];		/* run queue bitmap array */
	int					highq;				/* highest runnable queue */
	int					count;				/* # of runnable threads */
	int					depress_count;		/* # of depressed threads */
};

typedef struct run_queue	*run_queue_t;
#define RUN_QUEUE_NULL		((run_queue_t) 0)

#define csw_needed(thread, processor) (										\
	((thread)->state & TH_SUSP)										||		\
	((processor)->first_quantum?											\
	 ((processor)->runq.highq > (thread)->sched_pri				||			\
	  (processor)->processor_set->runq.highq > (thread)->sched_pri) :		\
	 ((processor)->runq.highq >= (thread)->sched_pri			||			\
	  (processor)->processor_set->runq.highq >= (thread)->sched_pri))	)

/*
 *	Scheduler routines.
 */

/* Remove thread from its run queue */
extern run_queue_t	rem_runq(
					thread_t	thread);

/* Mach factor computation (in mach_factor.c) */
extern void		compute_mach_factor(void);

/* Update threads quantum (in priority.c) */
extern void		thread_quantum_update(
					int			mycpu,
					thread_t	thread,
					int			nticks,
					int			state);

extern queue_head_t	action_queue;	/* assign/shutdown queue */

decl_simple_lock_data(,action_lock)

extern int		min_quantum;	/* defines max context switch rate */

/*
 *	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													\
	register 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_ */