xref: /csrg-svn/sys/kern/kern_synch.c (revision 8102)

/*	kern_synch.c	4.20	82/09/06	*/

#include "../h/param.h"
#include "../h/systm.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/proc.h"
#include "../h/file.h"
#include "../h/inode.h"
#include "../h/vm.h"
#include "../h/pte.h"
#include "../h/inline.h"
#include "../h/mtpr.h"
#ifdef MUSH
#include "../h/quota.h"
#include "../h/share.h"
#endif
#include "../h/kernel.h"
#include "../h/buf.h"

/*
 * Force switch among equal priority processes every 100ms.
 */
roundrobin()
{

	runrun++;
	aston();
	timeout(roundrobin, 0, hz / 10);
}

/*
 * The digital decay cpu usage priority assignment is scaled to run in
 * time as expanded by the 1 minute load average.  Each second we
 * multiply the the previous cpu usage estimate by
 *		nrscale*avenrun[0]
 * The following relates the load average to the period over which
 * cpu usage is 90% forgotten:
 *	loadav 1	 5 seconds
 *	loadav 5	24 seconds
 *	loadav 10	47 seconds
 *	loadav 20	93 seconds
 * This is a great improvement on the previous algorithm which
 * decayed the priorities by a constant, and decayed away all knowledge
 * of previous activity in about 20 seconds.  Under heavy load,
 * the previous algorithm degenerated to round-robin with poor response
 * time when there was a high load average.
 */
#undef ave
#define	ave(a,b) ((int)(((int)(a*b))/(b+1)))
int	nrscale = 2;
double	avenrun[];

/*
 * Constant for decay filter for cpu usage field
 * in process table (used by ps au).
 */
double	ccpu = 0.95122942450071400909;		/* exp(-1/20) */

#ifdef MELB
/*
 * Automatic niceness rate & max constants
 */
#define	MAXNICE	(8 + NZERO)	/* maximum auto nice value */
#define	NFACT	(40 * hz)	/* nice++ every 40 secs cpu+sys time */
#endif

/*
 * Recompute process priorities, once a second
 */
schedcpu()
{
	register struct proc *p;
	register int s, a;

	s = spl6(); time.tv_sec += lbolt / hz; lbolt %= hz; splx(s);
	wakeup((caddr_t)&lbolt);

	for (p = proc; p < procNPROC; p++) if (p->p_stat && p->p_stat!=SZOMB) {
#ifdef MUSH
		/*
		 * Charge process for memory in use
		 */
		if (p->p_quota->q_uid)
			p->p_quota->q_cost +=
			    shconsts.sc_click * p->p_rssize;
#endif
		if (p->p_time != 127)
			p->p_time++;
		if (timerisset(&p->p_seltimer) &&
		     --p->p_seltimer.tv_sec <= 0) {
			timerclear(&p->p_seltimer);
			s = spl6();
			switch (p->p_stat) {

			case SSLEEP:
				setrun(p);
				break;

			case SSTOP:
				unsleep(p);
				break;
			}
			splx(s);
		}
		if (timerisset(&p->p_realtimer.it_value) &&
		    itimerdecr(&p->p_realtimer, 1000000) == 0)
			psignal(p, SIGALRM);
		if (p->p_stat==SSLEEP || p->p_stat==SSTOP)
			if (p->p_slptime != 127)
				p->p_slptime++;
		if (p->p_flag&SLOAD)
			p->p_pctcpu = ccpu * p->p_pctcpu +
			    (1.0 - ccpu) * (p->p_cpticks/(float)hz);
		p->p_cpticks = 0;
#ifdef MUSH
		a = ave((p->p_cpu & 0377), avenrun[0]*nrscale) +
		     p->p_nice - NZERO + p->p_quota->q_nice;
#else
		a = ave((p->p_cpu & 0377), avenrun[0]*nrscale) +
		     p->p_nice - NZERO;
#endif
		if (a < 0)
			a = 0;
		if (a > 255)
			a = 255;
		p->p_cpu = a;
		(void) setpri(p);
		s = spl6();	/* prevent state changes */
		if (p->p_pri >= PUSER) {
			if ((p != u.u_procp || noproc) &&
			    p->p_stat == SRUN &&
			    (p->p_flag & SLOAD) &&
			    p->p_pri != p->p_usrpri) {
				remrq(p);
				p->p_pri = p->p_usrpri;
				setrq(p);
			} else
				p->p_pri = p->p_usrpri;
		}
		splx(s);
	}
	vmmeter();
	if (runin!=0) {
		runin = 0;
		wakeup((caddr_t)&runin);
	}
	if (bclnlist != NULL)
		wakeup((caddr_t)&proc[2]);
	timeout(schedcpu, 0, hz);
}

#define SQSIZE 0100	/* Must be power of 2 */
#define HASH(x)	(( (int) x >> 5) & (SQSIZE-1))
struct proc *slpque[SQSIZE];

/*
 * 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.
 * Callers of this routine must be prepared for
 * premature return, and check that the reason for
 * sleeping has gone away.
 */
sleep(chan, pri)
	caddr_t chan;
	int pri;
{
	register struct proc *rp, **hp;
	register s;

	rp = u.u_procp;
	s = spl6();
	if (chan==0 || rp->p_stat != SRUN || rp->p_rlink)
		panic("sleep");
	rp->p_wchan = chan;
	rp->p_slptime = 0;
	rp->p_pri = pri;
	hp = &slpque[HASH(chan)];
	rp->p_link = *hp;
	*hp = rp;
	if (pri > PZERO) {
		if (ISSIG(rp)) {
			if (rp->p_wchan)
				unsleep(rp);
			rp->p_stat = SRUN;
			(void) spl0();
			goto psig;
		}
		if (rp->p_wchan == 0)
			goto out;
		rp->p_stat = SSLEEP;
		(void) spl0();
		u.u_ru.ru_nvcsw++;
		swtch();
		if (ISSIG(rp))
			goto psig;
	} else {
		rp->p_stat = SSLEEP;
		(void) spl0();
		u.u_ru.ru_nvcsw++;
		swtch();
	}
out:
	splx(s);
	return;

	/*
	 * If priority was low (>PZERO) and
	 * there has been a signal, execute non-local goto through
	 * u.u_qsav, aborting the system call in progress (see trap.c)
	 * (or finishing a tsleep, see below)
	 */
psig:
	longjmp(u.u_qsav);
	/*NOTREACHED*/
}

/*
 * Sleep on chan at pri for at most a specified amount of time.
 * Return (TS_OK,TS_TIME,TS_SIG) on (normal,timeout,signal) condition.
 */
tsleep(chan, pri, tvp)
	caddr_t chan;
	int pri;
	struct timeval *tvp;
{
	register struct proc *p = u.u_procp;
	int s, rval;

	s = spl7();
	if (timercmp(tvp, &p->p_realtimer.it_value, >)) {
		/* alarm will occur first! */
		sleep(chan, pri);
		rval = TS_OK;		/* almost NOTREACHED modulo fuzz */
	} else {
		label_t lqsav;

		bcopy((caddr_t)u.u_qsav, (caddr_t)lqsav, sizeof (label_t));
		p->p_seltimer = *tvp;
		if (setjmp(u.u_qsav))
			rval = TS_SIG;
		else {
			sleep(chan, pri);
			rval = TS_OK;
		}
		timerclear(&p->p_seltimer);
		bcopy((caddr_t)lqsav, (caddr_t)u.u_qsav, sizeof (label_t));
	}
	splx(s);
	return (rval);
}

/*
 * Remove a process from its wait queue
 */
unsleep(p)
	register struct proc *p;
{
	register struct proc **hp;
	register s;

	s = spl6();
	if (p->p_wchan) {
		hp = &slpque[HASH(p->p_wchan)];
		while (*hp != p)
			hp = &(*hp)->p_link;
		*hp = p->p_link;
		p->p_wchan = 0;
	}
	splx(s);
}

/*
 * Wake up all processes sleeping on chan.
 */
wakeup(chan)
	register caddr_t chan;
{
	register struct proc *p, **q, **h;
	int s;

	s = spl6();
	h = &slpque[HASH(chan)];
restart:
	for (q = h; p = *q; ) {
		if (p->p_rlink || p->p_stat != SSLEEP && p->p_stat != SSTOP)
			panic("wakeup");
		if (p->p_wchan==chan) {
			p->p_wchan = 0;
			*q = p->p_link;
			p->p_slptime = 0;
			if (p->p_stat == SSLEEP) {
				/* OPTIMIZED INLINE EXPANSION OF setrun(p) */
				p->p_stat = SRUN;
				if (p->p_flag & SLOAD)
					setrq(p);
				if (p->p_pri < curpri) {
					runrun++;
					aston();
				}
				if ((p->p_flag&SLOAD) == 0) {
					if (runout != 0) {
						runout = 0;
						wakeup((caddr_t)&runout);
					}
					wantin++;
				}
				/* END INLINE EXPANSION */
				goto restart;
			}
		} else
			q = &p->p_link;
	}
	splx(s);
}

/*
 * Initialize the (doubly-linked) run queues
 * to be empty.
 */
rqinit()
{
	register int i;

	for (i = 0; i < NQS; i++)
		qs[i].ph_link = qs[i].ph_rlink = (struct proc *)&qs[i];
}

/*
 * Set the process running;
 * arrange for it to be swapped in if necessary.
 */
setrun(p)
	register struct proc *p;
{
	register int s;

	s = spl6();
	switch (p->p_stat) {

	case 0:
	case SWAIT:
	case SRUN:
	case SZOMB:
	default:
		panic("setrun");

	case SSTOP:
	case SSLEEP:
		unsleep(p);		/* e.g. when sending signals */
		break;

	case SIDL:
		break;
	}
	p->p_stat = SRUN;
	if (p->p_flag & SLOAD)
		setrq(p);
	splx(s);
	if (p->p_pri < curpri) {
		runrun++;
		aston();
	}
	if ((p->p_flag&SLOAD) == 0) {
		if (runout != 0) {
			runout = 0;
			wakeup((caddr_t)&runout);
		}
		wantin++;
	}
}

/*
 * Set user priority.
 * The rescheduling flag (runrun)
 * is set if the priority is better
 * than the currently running process.
 */
setpri(pp)
	register struct proc *pp;
{
	register int p;

	p = (pp->p_cpu & 0377)/4;
	p += PUSER + 2*(pp->p_nice - NZERO);
	if (pp->p_rssize > pp->p_maxrss && freemem < desfree)
		p += 2*4;	/* effectively, nice(4) */
	if (p > 127)
		p = 127;
	if (p < curpri) {
		runrun++;
		aston();
	}
	pp->p_usrpri = p;
	return (p);
}