[apple/xnu.git] / bsd / kern / kern_synch.c

/*
 * Copyright (c) 2000-2001 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ 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, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1987 Carnegie-Mellon University
 * All rights reserved.  The CMU software License Agreement specifies
 * the terms and conditions for use and redistribution.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/user.h>
#include <sys/file.h>
#include <sys/vnode.h>
#include <sys/kernel.h>
#include <sys/buf.h>

#include <machine/spl.h>

#include <kern/queue.h>
#include <sys/lock.h>
#include <kern/thread.h>
#include <kern/sched_prim.h>
#include <kern/ast.h>

#include <kern/cpu_number.h>
#include <vm/vm_kern.h>

#include <kern/task.h>
#include <mach/time_value.h>

#if KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif 

static void
_sleep_continue(void)
{
	register struct proc *p;
	register thread_t self = current_act();
	struct uthread * ut;
	int sig, catch;
	int error = 0;

	ut = get_bsdthread_info(self);
	catch = ut->uu_pri & PCATCH;
	p = current_proc();

	switch (get_thread_waitresult(self)) {
		case THREAD_TIMED_OUT:
			error = EWOULDBLOCK;
			break;
		case THREAD_AWAKENED:
			/*
			 * Posix implies any signal should be delivered
			 * first, regardless of whether awakened due
			 * to receiving event.
			 */
			if (!catch)
				break;
			/* else fall through */
		case THREAD_INTERRUPTED:
			if (catch) {
				if (thread_should_abort(self)) {
					error = EINTR;
				} else if (SHOULDissignal(p,ut)) {
					if (sig = CURSIG(p)) {
						if (p->p_sigacts->ps_sigintr & sigmask(sig))
							error = EINTR;
						else
							error = ERESTART;
					}
					if (thread_should_abort(self)) {
						error = EINTR;
					}
				}
			}  else
				error = EINTR;
			break;
	}

	if (error == EINTR || error == ERESTART)
		act_set_astbsd(self);

	if (ut->uu_timo)
		thread_cancel_timer();

#if KTRACE
	if (KTRPOINT(p, KTR_CSW))
		ktrcsw(p->p_tracep, 0, 0, -1);
#endif

	unix_syscall_return((*ut->uu_continuation)(error));
}

/*
 * Give up the processor till a wakeup occurs
 * on chan, at which time the process
 * enters the scheduling queue at priority pri.
 * The most important effect of pri is that when
 * pri<=PZERO a signal cannot disturb the sleep;
 * if pri>PZERO signals will be processed.
 * If pri&PCATCH is set, signals will cause sleep
 * to return 1, rather than longjmp.
 * Callers of this routine must be prepared for
 * premature return, and check that the reason for
 * sleeping has gone away.
 */

static int
_sleep(
	caddr_t		chan,
	int			pri,
	char		*wmsg,
	u_int64_t	abstime,
	int			(*continuation)(int))
{
	register struct proc *p;
	register thread_t self = current_act();
	struct uthread * ut;
	int sig, catch = pri & PCATCH;
	int sigttblock = pri & PTTYBLOCK;
	int wait_result;
	int error = 0;
	spl_t	s;

	s = splhigh();

	ut = get_bsdthread_info(self);
	
	p = current_proc();
#if KTRACE
	if (KTRPOINT(p, KTR_CSW))
		ktrcsw(p->p_tracep, 1, 0, -1);
#endif	
	p->p_priority = pri & PRIMASK;
		
	if (chan != NULL)
		assert_wait_prim(chan, NULL, abstime,
							(catch) ? THREAD_ABORTSAFE : THREAD_UNINT);
	else
	if (abstime != 0)
		thread_set_timer_deadline(abstime);

	/*
	 * We start our timeout
	 * before calling CURSIG, as we could stop there, and a wakeup
	 * or a SIGCONT (or both) could occur while we were stopped.
	 * A SIGCONT would cause us to be marked as SSLEEP
	 * without resuming us, thus we must be ready for sleep
	 * when CURSIG is called.  If the wakeup happens while we're
	 * stopped, p->p_wchan will be 0 upon return from CURSIG.
	 */
	if (catch) {
		if (SHOULDissignal(p,ut)) {
			if (sig = CURSIG(p)) {
				if (clear_wait(self, THREAD_INTERRUPTED) == KERN_FAILURE)
					goto block;
				/* if SIGTTOU or SIGTTIN then block till SIGCONT */
				if (sigttblock && ((sig == SIGTTOU) || (sig == SIGTTIN))) {
					p->p_flag |= P_TTYSLEEP;
					/* reset signal bits */
					clear_procsiglist(p, sig);
					assert_wait(&p->p_siglist, THREAD_ABORTSAFE);
					/* assert wait can block and SIGCONT should be checked */
					if (p->p_flag & P_TTYSLEEP)
						thread_block(THREAD_CONTINUE_NULL);
					/* return with success */
					error = 0;
					goto out;
				}
				if (p->p_sigacts->ps_sigintr & sigmask(sig))
					error = EINTR;
				else
					error = ERESTART;
				goto out;
			}
		}
		if (thread_should_abort(self)) {
			if (clear_wait(self, THREAD_INTERRUPTED) == KERN_FAILURE)
				goto block;
			error = EINTR;
			goto out;
		}
		if (get_thread_waitresult(self) != THREAD_WAITING) {
			/*already happened */
			goto out;
		}
	}

block:

	splx(s);
	p->p_stats->p_ru.ru_nvcsw++;

	if ((thread_continue_t)continuation != THREAD_CONTINUE_NULL ) {
	  ut->uu_continuation = continuation;
	  ut->uu_pri = pri;
	  ut->uu_timo = abstime? 1: 0;
	  (void) thread_block(_sleep_continue);
	  /* NOTREACHED */
	}

	wait_result = thread_block(THREAD_CONTINUE_NULL);

	switch (wait_result) {
		case THREAD_TIMED_OUT:
			error = EWOULDBLOCK;
			break;
		case THREAD_AWAKENED:
			/*
			 * Posix implies any signal should be delivered
			 * first, regardless of whether awakened due
			 * to receiving event.
			 */
			if (!catch)
				break;
			/* else fall through */
		case THREAD_INTERRUPTED:
			if (catch) {
				if (thread_should_abort(self)) {
					error = EINTR;
				} else if (SHOULDissignal(p,ut)) {
					if (sig = CURSIG(p)) {
						if (p->p_sigacts->ps_sigintr & sigmask(sig))
							error = EINTR;
						else
							error = ERESTART;
					}
					if (thread_should_abort(self)) {
						error = EINTR;
					}
				}
			}  else
				error = EINTR;
			break;
	}
out:
	if (error == EINTR || error == ERESTART)
		act_set_astbsd(self);
	if (abstime)
		thread_cancel_timer();
	(void) splx(s);
#if KTRACE
	if (KTRPOINT(p, KTR_CSW))
		ktrcsw(p->p_tracep, 0, 0, -1);
#endif
	return (error);
}

int
sleep(
	void	*chan,
	int		pri)
{
	return _sleep((caddr_t)chan, pri, (char *)NULL, 0, (int (*)(int))0);
}

int
tsleep(
	void	*chan,
	int		pri,
	char	*wmsg,
	int		timo)
{
	u_int64_t	abstime = 0;

	if (timo)
		clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
	return _sleep((caddr_t)chan, pri, wmsg, abstime, (int (*)(int))0);
}

int
tsleep0(
	void	*chan,
	int		pri,
	char	*wmsg,
	int		timo,
	int		(*continuation)(int))
{			
	u_int64_t	abstime = 0;

	if (timo)
		clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
	return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation);
}

int
tsleep1(
	void		*chan,
	int			pri,
	char		*wmsg,
	u_int64_t	abstime,
	int			(*continuation)(int))
{			
	return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation);
}

/*
 * Wake up all processes sleeping on chan.
 */
void
wakeup(chan)
	register void *chan;
{
	thread_wakeup_prim((caddr_t)chan, FALSE, THREAD_AWAKENED);
}

/*
 * Wake up the first process sleeping on chan.
 *
 * Be very sure that the first process is really
 * the right one to wakeup.
 */
void
wakeup_one(chan)
	register caddr_t chan;
{
	thread_wakeup_prim((caddr_t)chan, TRUE, THREAD_AWAKENED);
}

/*
 * Compute the priority of a process when running in user mode.
 * Arrange to reschedule if the resulting priority is better
 * than that of the current process.
 */
void
resetpriority(p)
	register struct proc *p;
{
	(void)task_importance(p->task, -p->p_nice);
}

struct loadavg averunnable =
	{ {0, 0, 0}, FSCALE };		/* load average, of runnable procs */
/*
 * Constants for averages over 1, 5, and 15 minutes
 * when sampling at 5 second intervals.
 */
static fixpt_t cexp[3] = {
    (fixpt_t)(0.9200444146293232 * FSCALE),    /* exp(-1/12) */
    (fixpt_t)(0.9834714538216174 * FSCALE),    /* exp(-1/60) */
    (fixpt_t)(0.9944598480048967 * FSCALE),    /* exp(-1/180) */
};

void
compute_averunnable(
	register int	nrun)
{
	register int		i;
	struct loadavg		*avg = &averunnable;

    for (i = 0; i < 3; i++)
        avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
            nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
}
Commit	Line	Data
1c79356b	1	/*
9bccf70c	2	* Copyright (c) 2000-2001 Apple Computer, Inc. All rights reserved.
1c79356b A	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
43866e37	6	* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
1c79356b	7	*
43866e37 A	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
1c79356b A	17	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
1c79356b A	18	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
43866e37 A	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.
1c79356b A	22	*
	23	* @APPLE_LICENSE_HEADER_END@
	24	*/
	25	/*
	26	* Mach Operating System
	27	* Copyright (c) 1987 Carnegie-Mellon University
	28	* All rights reserved. The CMU software License Agreement specifies
	29	* the terms and conditions for use and redistribution.
	30	*/
	31
	32	#include <sys/param.h>
	33	#include <sys/systm.h>
	34	#include <sys/proc.h>
	35	#include <sys/user.h>
	36	#include <sys/file.h>
	37	#include <sys/vnode.h>
	38	#include <sys/kernel.h>
	39	#include <sys/buf.h>
	40
	41	#include <machine/spl.h>
	42
	43	#include <kern/queue.h>
	44	#include <sys/lock.h>
	45	#include <kern/thread.h>
9bccf70c	46	#include <kern/sched_prim.h>
1c79356b A	47	#include <kern/ast.h>
	48
	49	#include <kern/cpu_number.h>
	50	#include <vm/vm_kern.h>
	51
	52	#include <kern/task.h>
	53	#include <mach/time_value.h>
	54
9bccf70c A	55	#if KTRACE
	56	#include <sys/uio.h>
	57	#include <sys/ktrace.h>
	58	#endif
	59
	60	static void
	61	_sleep_continue(void)
1c79356b A	62	{
1c79356b A	63	register struct proc *p;
55e303ae	64	register thread_t self = current_act();
1c79356b A	65	struct uthread * ut;
	66	int sig, catch;
	67	int error = 0;
	68
55e303ae	69	ut = get_bsdthread_info(self);
1c79356b A	70	catch = ut->uu_pri & PCATCH;
	71	p = current_proc();
	72
55e303ae	73	switch (get_thread_waitresult(self)) {
1c79356b A	74	case THREAD_TIMED_OUT:
	75	error = EWOULDBLOCK;
	76	break;
	77	case THREAD_AWAKENED:
	78	/*
	79	* Posix implies any signal should be delivered
	80	* first, regardless of whether awakened due
	81	* to receiving event.
	82	*/
	83	if (!catch)
	84	break;
	85	/* else fall through */
	86	case THREAD_INTERRUPTED:
	87	if (catch) {
55e303ae	88	if (thread_should_abort(self)) {
1c79356b A	89	error = EINTR;
	90	} else if (SHOULDissignal(p,ut)) {
	91	if (sig = CURSIG(p)) {
	92	if (p->p_sigacts->ps_sigintr & sigmask(sig))
	93	error = EINTR;
	94	else
	95	error = ERESTART;
	96	}
55e303ae	97	if (thread_should_abort(self)) {
1c79356b A	98	error = EINTR;
	99	}
	100	}
1c79356b A	101	} else
	102	error = EINTR;
	103	break;
	104	}
	105
9bccf70c	106	if (error == EINTR \|\| error == ERESTART)
55e303ae	107	act_set_astbsd(self);
9bccf70c	108
1c79356b A	109	if (ut->uu_timo)
	110	thread_cancel_timer();
	111
9bccf70c A	112	#if KTRACE
	113	if (KTRPOINT(p, KTR_CSW))
	114	ktrcsw(p->p_tracep, 0, 0, -1);
	115	#endif
	116
1c79356b A	117	unix_syscall_return((*ut->uu_continuation)(error));
	118	}
	119
	120	/*
	121	* Give up the processor till a wakeup occurs
	122	* on chan, at which time the process
	123	* enters the scheduling queue at priority pri.
	124	* The most important effect of pri is that when
	125	* pri<=PZERO a signal cannot disturb the sleep;
	126	* if pri>PZERO signals will be processed.
	127	* If pri&PCATCH is set, signals will cause sleep
	128	* to return 1, rather than longjmp.
	129	* Callers of this routine must be prepared for
	130	* premature return, and check that the reason for
	131	* sleeping has gone away.
	132	*/
	133
9bccf70c A	134	static int
	135	_sleep(
	136	caddr_t chan,
	137	int pri,
	138	char *wmsg,
	139	u_int64_t abstime,
	140	int (*continuation)(int))
1c79356b A	141	{
1c79356b A	142	register struct proc *p;
55e303ae	143	register thread_t self = current_act();
1c79356b A	144	struct uthread * ut;
	145	int sig, catch = pri & PCATCH;
	146	int sigttblock = pri & PTTYBLOCK;
9bccf70c	147	int wait_result;
1c79356b A	148	int error = 0;
	149	spl_t s;
	150
	151	s = splhigh();
	152
55e303ae	153	ut = get_bsdthread_info(self);
1c79356b A	154
	155	p = current_proc();
	156	#if KTRACE
	157	if (KTRPOINT(p, KTR_CSW))
9bccf70c	158	ktrcsw(p->p_tracep, 1, 0, -1);
1c79356b A	159	#endif
	160	p->p_priority = pri & PRIMASK;
	161
55e303ae A	162	if (chan != NULL)
	163	assert_wait_prim(chan, NULL, abstime,
	164	(catch) ? THREAD_ABORTSAFE : THREAD_UNINT);
	165	else
	166	if (abstime != 0)
9bccf70c	167	thread_set_timer_deadline(abstime);
0b4e3aa0	168
1c79356b A	169	/*
	170	* We start our timeout
	171	* before calling CURSIG, as we could stop there, and a wakeup
	172	* or a SIGCONT (or both) could occur while we were stopped.
	173	* A SIGCONT would cause us to be marked as SSLEEP
	174	* without resuming us, thus we must be ready for sleep
	175	* when CURSIG is called. If the wakeup happens while we're
	176	* stopped, p->p_wchan will be 0 upon return from CURSIG.
	177	*/
	178	if (catch) {
1c79356b A	179	if (SHOULDissignal(p,ut)) {
1c79356b A	180	if (sig = CURSIG(p)) {
55e303ae A	181	if (clear_wait(self, THREAD_INTERRUPTED) == KERN_FAILURE)
55e303ae A	182	goto block;
1c79356b A	183	/* if SIGTTOU or SIGTTIN then block till SIGCONT */
	184	if (sigttblock && ((sig == SIGTTOU) \|\| (sig == SIGTTIN))) {
	185	p->p_flag \|= P_TTYSLEEP;
	186	/* reset signal bits */
9bccf70c	187	clear_procsiglist(p, sig);
1c79356b A	188	assert_wait(&p->p_siglist, THREAD_ABORTSAFE);
	189	/* assert wait can block and SIGCONT should be checked */
	190	if (p->p_flag & P_TTYSLEEP)
9bccf70c	191	thread_block(THREAD_CONTINUE_NULL);
1c79356b A	192	/* return with success */
	193	error = 0;
	194	goto out;
	195	}
	196	if (p->p_sigacts->ps_sigintr & sigmask(sig))
	197	error = EINTR;
	198	else
	199	error = ERESTART;
1c79356b A	200	goto out;
	201	}
	202	}
55e303ae A	203	if (thread_should_abort(self)) {
	204	if (clear_wait(self, THREAD_INTERRUPTED) == KERN_FAILURE)
	205	goto block;
1c79356b	206	error = EINTR;
1c79356b A	207	goto out;
1c79356b A	208	}
55e303ae	209	if (get_thread_waitresult(self) != THREAD_WAITING) {
9bccf70c	210	/already happened /
1c79356b A	211	goto out;
1c79356b A	212	}
1c79356b A	213	}
1c79356b A	214
55e303ae A	215	block:
55e303ae A	216
1c79356b A	217	splx(s);
	218	p->p_stats->p_ru.ru_nvcsw++;
	219
55e303ae	220	if ((thread_continue_t)continuation != THREAD_CONTINUE_NULL ) {
1c79356b A	221	ut->uu_continuation = continuation;
1c79356b A	222	ut->uu_pri = pri;
9bccf70c A	223	ut->uu_timo = abstime? 1: 0;
9bccf70c A	224	(void) thread_block(_sleep_continue);
1c79356b A	225	/* NOTREACHED */
	226	}
	227
9bccf70c	228	wait_result = thread_block(THREAD_CONTINUE_NULL);
1c79356b	229
9bccf70c	230	switch (wait_result) {
1c79356b A	231	case THREAD_TIMED_OUT:
	232	error = EWOULDBLOCK;
	233	break;
	234	case THREAD_AWAKENED:
	235	/*
	236	* Posix implies any signal should be delivered
	237	* first, regardless of whether awakened due
	238	* to receiving event.
	239	*/
	240	if (!catch)
	241	break;
	242	/* else fall through */
	243	case THREAD_INTERRUPTED:
	244	if (catch) {
55e303ae	245	if (thread_should_abort(self)) {
1c79356b A	246	error = EINTR;
	247	} else if (SHOULDissignal(p,ut)) {
	248	if (sig = CURSIG(p)) {
	249	if (p->p_sigacts->ps_sigintr & sigmask(sig))
	250	error = EINTR;
	251	else
	252	error = ERESTART;
	253	}
55e303ae	254	if (thread_should_abort(self)) {
1c79356b A	255	error = EINTR;
	256	}
	257	}
1c79356b A	258	} else
	259	error = EINTR;
	260	break;
	261	}
	262	out:
9bccf70c	263	if (error == EINTR \|\| error == ERESTART)
55e303ae	264	act_set_astbsd(self);
9bccf70c	265	if (abstime)
1c79356b A	266	thread_cancel_timer();
1c79356b A	267	(void) splx(s);
9bccf70c A	268	#if KTRACE
	269	if (KTRPOINT(p, KTR_CSW))
	270	ktrcsw(p->p_tracep, 0, 0, -1);
	271	#endif
1c79356b A	272	return (error);
	273	}
	274
9bccf70c A	275	int
	276	sleep(
	277	void *chan,
	278	int pri)
1c79356b	279	{
9bccf70c	280	return _sleep((caddr_t)chan, pri, (char )NULL, 0, (int ()(int))0);
1c79356b A	281	}
1c79356b A	282
9bccf70c A	283	int
	284	tsleep(
	285	void *chan,
	286	int pri,
	287	char *wmsg,
	288	int timo)
	289	{
	290	u_int64_t abstime = 0;
	291
	292	if (timo)
	293	clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
	294	return _sleep((caddr_t)chan, pri, wmsg, abstime, (int (*)(int))0);
1c79356b A	295	}
1c79356b A	296
9bccf70c A	297	int
	298	tsleep0(
	299	void *chan,
	300	int pri,
	301	char *wmsg,
	302	int timo,
	303	int (*continuation)(int))
1c79356b	304	{
9bccf70c A	305	u_int64_t abstime = 0;
	306
	307	if (timo)
	308	clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
	309	return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation);
0b4e3aa0 A	310	}
0b4e3aa0 A	311
9bccf70c A	312	int
	313	tsleep1(
	314	void *chan,
	315	int pri,
	316	char *wmsg,
	317	u_int64_t abstime,
	318	int (*continuation)(int))
0b4e3aa0	319	{
9bccf70c	320	return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation);
1c79356b A	321	}
	322
	323	/*
	324	* Wake up all processes sleeping on chan.
	325	*/
	326	void
	327	wakeup(chan)
	328	register void *chan;
	329	{
9bccf70c	330	thread_wakeup_prim((caddr_t)chan, FALSE, THREAD_AWAKENED);
1c79356b A	331	}
	332
	333	/*
	334	* Wake up the first process sleeping on chan.
	335	*
	336	* Be very sure that the first process is really
	337	* the right one to wakeup.
	338	*/
9bccf70c	339	void
1c79356b A	340	wakeup_one(chan)
	341	register caddr_t chan;
	342	{
	343	thread_wakeup_prim((caddr_t)chan, TRUE, THREAD_AWAKENED);
	344	}
	345
	346	/*
	347	* Compute the priority of a process when running in user mode.
	348	* Arrange to reschedule if the resulting priority is better
	349	* than that of the current process.
	350	*/
	351	void
	352	resetpriority(p)
	353	register struct proc *p;
	354	{
0b4e3aa0	355	(void)task_importance(p->task, -p->p_nice);
1c79356b	356	}
9bccf70c A	357
	358	struct loadavg averunnable =
	359	{ {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
	360	/*
	361	* Constants for averages over 1, 5, and 15 minutes
	362	* when sampling at 5 second intervals.
	363	*/
	364	static fixpt_t cexp[3] = {
	365	(fixpt_t)(0.9200444146293232 * FSCALE), /* exp(-1/12) */
	366	(fixpt_t)(0.9834714538216174 * FSCALE), /* exp(-1/60) */
	367	(fixpt_t)(0.9944598480048967 * FSCALE), /* exp(-1/180) */
	368	};
	369
	370	void
	371	compute_averunnable(
	372	register int nrun)
	373	{
	374	register int i;
	375	struct loadavg *avg = &averunnable;
	376
	377	for (i = 0; i < 3; i++)
	378	avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
	379	nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
	380	}