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

/*
 * Copyright (c) 2000-2001 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (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.
 * 
 * This 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
 * 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 thread = current_thread();
	thread_act_t th_act;
	struct uthread * ut;
	int sig, catch;
	int error = 0;

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

#if FIXME  /* [ */
	thread->wait_mesg = NULL;
#endif  /* FIXME ] */
	switch (get_thread_waitresult(thread)) {
		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(current_thread())) {
					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(current_thread())) {
						error = EINTR;
					}
				}
			}  else
				error = EINTR;
			break;
	}

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

	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 thread = current_thread();
	thread_act_t th_act;
	struct uthread * ut;
	int sig, catch = pri & PCATCH;
	int sigttblock = pri & PTTYBLOCK;
	int wait_result;
	int error = 0;
	spl_t	s;

	s = splhigh();

	th_act = current_act();
	ut = get_bsdthread_info(th_act);
	
	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)
		wait_result = assert_wait(chan,
								  (catch) ? THREAD_ABORTSAFE : THREAD_UNINT);

	if (abstime)
		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)) {
				clear_wait(thread, THREAD_INTERRUPTED);
				/* 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(current_thread())) {
			clear_wait(thread, THREAD_INTERRUPTED);
			error = EINTR;
			goto out;
		}
		if (get_thread_waitresult(thread) != THREAD_WAITING) {
			/*already happened */
			goto out;
		}
	}

#if FIXME  /* [ */
	thread->wait_mesg = wmsg;
#endif  /* FIXME ] */
	splx(s);
	p->p_stats->p_ru.ru_nvcsw++;

	if (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);

#if FIXME  /* [ */
	thread->wait_mesg = NULL;
#endif  /* FIXME ] */
	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(current_thread())) {
					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(current_thread())) {
						error = EINTR;
					}
				}
			}  else
				error = EINTR;
			break;
	}
out:
	if (error == EINTR || error == ERESTART)
		act_set_astbsd(th_act);
	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	*
de355530 A	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
1c79356b	11	*
de355530 A	12	* This Original Code and all software distributed under the License are
de355530 A	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
1c79356b A	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
1c79356b A	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
de355530 A	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
1c79356b A	19	*
	20	* @APPLE_LICENSE_HEADER_END@
	21	*/
	22	/*
	23	* Mach Operating System
	24	* Copyright (c) 1987 Carnegie-Mellon University
	25	* All rights reserved. The CMU software License Agreement specifies
	26	* the terms and conditions for use and redistribution.
	27	*/
	28
	29	#include <sys/param.h>
	30	#include <sys/systm.h>
	31	#include <sys/proc.h>
	32	#include <sys/user.h>
	33	#include <sys/file.h>
	34	#include <sys/vnode.h>
	35	#include <sys/kernel.h>
	36	#include <sys/buf.h>
	37
	38	#include <machine/spl.h>
	39
	40	#include <kern/queue.h>
	41	#include <sys/lock.h>
	42	#include <kern/thread.h>
9bccf70c	43	#include <kern/sched_prim.h>
1c79356b A	44	#include <kern/ast.h>
	45
	46	#include <kern/cpu_number.h>
	47	#include <vm/vm_kern.h>
	48
	49	#include <kern/task.h>
	50	#include <mach/time_value.h>
	51
9bccf70c A	52	#if KTRACE
	53	#include <sys/uio.h>
	54	#include <sys/ktrace.h>
	55	#endif
	56
	57	static void
	58	_sleep_continue(void)
1c79356b A	59	{
	60	register struct proc *p;
	61	register thread_t thread = current_thread();
	62	thread_act_t th_act;
	63	struct uthread * ut;
	64	int sig, catch;
	65	int error = 0;
	66
	67	th_act = current_act();
	68	ut = get_bsdthread_info(th_act);
	69	catch = ut->uu_pri & PCATCH;
	70	p = current_proc();
	71
	72	#if FIXME /* [ */
	73	thread->wait_mesg = NULL;
	74	#endif /* FIXME ] */
	75	switch (get_thread_waitresult(thread)) {
	76	case THREAD_TIMED_OUT:
	77	error = EWOULDBLOCK;
	78	break;
	79	case THREAD_AWAKENED:
	80	/*
	81	* Posix implies any signal should be delivered
	82	* first, regardless of whether awakened due
	83	* to receiving event.
	84	*/
	85	if (!catch)
	86	break;
	87	/* else fall through */
	88	case THREAD_INTERRUPTED:
	89	if (catch) {
1c79356b A	90	if (thread_should_abort(current_thread())) {
	91	error = EINTR;
	92	} else if (SHOULDissignal(p,ut)) {
	93	if (sig = CURSIG(p)) {
	94	if (p->p_sigacts->ps_sigintr & sigmask(sig))
	95	error = EINTR;
	96	else
	97	error = ERESTART;
	98	}
	99	if (thread_should_abort(current_thread())) {
	100	error = EINTR;
	101	}
	102	}
1c79356b A	103	} else
	104	error = EINTR;
	105	break;
	106	}
	107
9bccf70c A	108	if (error == EINTR \|\| error == ERESTART)
	109	act_set_astbsd(th_act);
	110
1c79356b A	111	if (ut->uu_timo)
	112	thread_cancel_timer();
	113
9bccf70c A	114	#if KTRACE
	115	if (KTRPOINT(p, KTR_CSW))
	116	ktrcsw(p->p_tracep, 0, 0, -1);
	117	#endif
	118
1c79356b A	119	unix_syscall_return((*ut->uu_continuation)(error));
	120	}
	121
	122	/*
	123	* Give up the processor till a wakeup occurs
	124	* on chan, at which time the process
	125	* enters the scheduling queue at priority pri.
	126	* The most important effect of pri is that when
	127	* pri<=PZERO a signal cannot disturb the sleep;
	128	* if pri>PZERO signals will be processed.
	129	* If pri&PCATCH is set, signals will cause sleep
	130	* to return 1, rather than longjmp.
	131	* Callers of this routine must be prepared for
	132	* premature return, and check that the reason for
	133	* sleeping has gone away.
	134	*/
	135
9bccf70c A	136	static int
	137	_sleep(
	138	caddr_t chan,
	139	int pri,
	140	char *wmsg,
	141	u_int64_t abstime,
	142	int (*continuation)(int))
1c79356b A	143	{
	144	register struct proc *p;
	145	register thread_t thread = current_thread();
	146	thread_act_t th_act;
	147	struct uthread * ut;
	148	int sig, catch = pri & PCATCH;
	149	int sigttblock = pri & PTTYBLOCK;
9bccf70c	150	int wait_result;
1c79356b A	151	int error = 0;
	152	spl_t s;
	153
	154	s = splhigh();
	155
	156	th_act = current_act();
	157	ut = get_bsdthread_info(th_act);
	158
	159	p = current_proc();
	160	#if KTRACE
	161	if (KTRPOINT(p, KTR_CSW))
9bccf70c	162	ktrcsw(p->p_tracep, 1, 0, -1);
1c79356b A	163	#endif
	164	p->p_priority = pri & PRIMASK;
	165
9bccf70c A	166	if (chan)
	167	wait_result = assert_wait(chan,
	168	(catch) ? THREAD_ABORTSAFE : THREAD_UNINT);
	169
	170	if (abstime)
	171	thread_set_timer_deadline(abstime);
0b4e3aa0	172
1c79356b A	173	/*
	174	* We start our timeout
	175	* before calling CURSIG, as we could stop there, and a wakeup
	176	* or a SIGCONT (or both) could occur while we were stopped.
	177	* A SIGCONT would cause us to be marked as SSLEEP
	178	* without resuming us, thus we must be ready for sleep
	179	* when CURSIG is called. If the wakeup happens while we're
	180	* stopped, p->p_wchan will be 0 upon return from CURSIG.
	181	*/
	182	if (catch) {
1c79356b A	183	if (SHOULDissignal(p,ut)) {
	184	if (sig = CURSIG(p)) {
	185	clear_wait(thread, THREAD_INTERRUPTED);
	186	/* if SIGTTOU or SIGTTIN then block till SIGCONT */
	187	if (sigttblock && ((sig == SIGTTOU) \|\| (sig == SIGTTIN))) {
	188	p->p_flag \|= P_TTYSLEEP;
	189	/* reset signal bits */
9bccf70c	190	clear_procsiglist(p, sig);
1c79356b A	191	assert_wait(&p->p_siglist, THREAD_ABORTSAFE);
	192	/* assert wait can block and SIGCONT should be checked */
	193	if (p->p_flag & P_TTYSLEEP)
9bccf70c	194	thread_block(THREAD_CONTINUE_NULL);
1c79356b A	195	/* return with success */
	196	error = 0;
	197	goto out;
	198	}
	199	if (p->p_sigacts->ps_sigintr & sigmask(sig))
	200	error = EINTR;
	201	else
	202	error = ERESTART;
1c79356b A	203	goto out;
	204	}
	205	}
	206	if (thread_should_abort(current_thread())) {
	207	clear_wait(thread, THREAD_INTERRUPTED);
	208	error = EINTR;
1c79356b A	209	goto out;
1c79356b A	210	}
9bccf70c A	211	if (get_thread_waitresult(thread) != THREAD_WAITING) {
9bccf70c A	212	/already happened /
1c79356b A	213	goto out;
1c79356b A	214	}
1c79356b A	215	}
	216
	217	#if FIXME /* [ */
	218	thread->wait_mesg = wmsg;
	219	#endif /* FIXME ] */
	220	splx(s);
	221	p->p_stats->p_ru.ru_nvcsw++;
	222
9bccf70c	223	if (continuation != THREAD_CONTINUE_NULL ) {
1c79356b A	224	ut->uu_continuation = continuation;
1c79356b A	225	ut->uu_pri = pri;
9bccf70c A	226	ut->uu_timo = abstime? 1: 0;
9bccf70c A	227	(void) thread_block(_sleep_continue);
1c79356b A	228	/* NOTREACHED */
	229	}
	230
9bccf70c	231	wait_result = thread_block(THREAD_CONTINUE_NULL);
1c79356b A	232
	233	#if FIXME /* [ */
	234	thread->wait_mesg = NULL;
	235	#endif /* FIXME ] */
9bccf70c	236	switch (wait_result) {
1c79356b A	237	case THREAD_TIMED_OUT:
	238	error = EWOULDBLOCK;
	239	break;
	240	case THREAD_AWAKENED:
	241	/*
	242	* Posix implies any signal should be delivered
	243	* first, regardless of whether awakened due
	244	* to receiving event.
	245	*/
	246	if (!catch)
	247	break;
	248	/* else fall through */
	249	case THREAD_INTERRUPTED:
	250	if (catch) {
1c79356b A	251	if (thread_should_abort(current_thread())) {
	252	error = EINTR;
	253	} else if (SHOULDissignal(p,ut)) {
	254	if (sig = CURSIG(p)) {
	255	if (p->p_sigacts->ps_sigintr & sigmask(sig))
	256	error = EINTR;
	257	else
	258	error = ERESTART;
	259	}
	260	if (thread_should_abort(current_thread())) {
	261	error = EINTR;
	262	}
	263	}
1c79356b A	264	} else
	265	error = EINTR;
	266	break;
	267	}
	268	out:
9bccf70c A	269	if (error == EINTR \|\| error == ERESTART)
	270	act_set_astbsd(th_act);
	271	if (abstime)
1c79356b A	272	thread_cancel_timer();
1c79356b A	273	(void) splx(s);
9bccf70c A	274	#if KTRACE
	275	if (KTRPOINT(p, KTR_CSW))
	276	ktrcsw(p->p_tracep, 0, 0, -1);
	277	#endif
1c79356b A	278	return (error);
	279	}
	280
9bccf70c A	281	int
	282	sleep(
	283	void *chan,
	284	int pri)
1c79356b	285	{
9bccf70c	286	return _sleep((caddr_t)chan, pri, (char )NULL, 0, (int ()(int))0);
1c79356b A	287	}
1c79356b A	288
9bccf70c A	289	int
	290	tsleep(
	291	void *chan,
	292	int pri,
	293	char *wmsg,
	294	int timo)
	295	{
	296	u_int64_t abstime = 0;
	297
	298	if (timo)
	299	clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
	300	return _sleep((caddr_t)chan, pri, wmsg, abstime, (int (*)(int))0);
1c79356b A	301	}
1c79356b A	302
9bccf70c A	303	int
	304	tsleep0(
	305	void *chan,
	306	int pri,
	307	char *wmsg,
	308	int timo,
	309	int (*continuation)(int))
1c79356b	310	{
9bccf70c A	311	u_int64_t abstime = 0;
	312
	313	if (timo)
	314	clock_interval_to_deadline(timo, NSEC_PER_SEC / hz, &abstime);
	315	return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation);
0b4e3aa0 A	316	}
0b4e3aa0 A	317
9bccf70c A	318	int
	319	tsleep1(
	320	void *chan,
	321	int pri,
	322	char *wmsg,
	323	u_int64_t abstime,
	324	int (*continuation)(int))
0b4e3aa0	325	{
9bccf70c	326	return _sleep((caddr_t)chan, pri, wmsg, abstime, continuation);
1c79356b A	327	}
	328
	329	/*
	330	* Wake up all processes sleeping on chan.
	331	*/
	332	void
	333	wakeup(chan)
	334	register void *chan;
	335	{
9bccf70c	336	thread_wakeup_prim((caddr_t)chan, FALSE, THREAD_AWAKENED);
1c79356b A	337	}
	338
	339	/*
	340	* Wake up the first process sleeping on chan.
	341	*
	342	* Be very sure that the first process is really
	343	* the right one to wakeup.
	344	*/
9bccf70c	345	void
1c79356b A	346	wakeup_one(chan)
	347	register caddr_t chan;
	348	{
	349	thread_wakeup_prim((caddr_t)chan, TRUE, THREAD_AWAKENED);
	350	}
	351
	352	/*
	353	* Compute the priority of a process when running in user mode.
	354	* Arrange to reschedule if the resulting priority is better
	355	* than that of the current process.
	356	*/
	357	void
	358	resetpriority(p)
	359	register struct proc *p;
	360	{
0b4e3aa0	361	(void)task_importance(p->task, -p->p_nice);
1c79356b	362	}
9bccf70c A	363
	364	struct loadavg averunnable =
	365	{ {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
	366	/*
	367	* Constants for averages over 1, 5, and 15 minutes
	368	* when sampling at 5 second intervals.
	369	*/
	370	static fixpt_t cexp[3] = {
	371	(fixpt_t)(0.9200444146293232 * FSCALE), /* exp(-1/12) */
	372	(fixpt_t)(0.9834714538216174 * FSCALE), /* exp(-1/60) */
	373	(fixpt_t)(0.9944598480048967 * FSCALE), /* exp(-1/180) */
	374	};
	375
	376	void
	377	compute_averunnable(
	378	register int nrun)
	379	{
	380	register int i;
	381	struct loadavg *avg = &averunnable;
	382
	383	for (i = 0; i < 3; i++)
	384	avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
	385	nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
	386	}