Source to kern/sched.h

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
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 * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
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 * Source License Version 1.0 (the 'License').  You may not use this file
 * except in compliance with the License.  Please obtain a copy of the
 * License at http://www.apple.com/publicsource and read it before using
 * this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
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 * @APPLE_LICENSE_HEADER_END@
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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_

#ifdef	KERNEL_BUILD
#include <cpus.h>
#include <mach_fixpri.h>
#include <simple_clock.h>
#include <stat_time.h>
#else	/* KERNEL_BUILD */
#include <mach/features.h>
#endif	/* KERNEL_BUILD */

#include <kern/queue.h>
#include <kern/lock.h>
#include <kern/macro_help.h>

#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	32			/* 32 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			high;		/* high queue value */
	int			count;		/* count of threads runable */
};

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)->runq.count > 0) ||				  \
	(((processor)->processor_set->runq.count > 0) &&		  \
	 ((processor)->first_quantum?					  \
	  (processor)->processor_set->runq.high > (thread)->sched_pri :	  \
	  (processor)->processor_set->runq.high >= (thread)->sched_pri)))

/*
 *	Scheduler routines.
 */

extern struct run_queue	*rem_runq();
extern struct thread	*choose_thread();
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	24
#define MAXPRI_USER	18
#define BASEPRI_USER	10

/*
 *	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							\
	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_ */