/*	vm_meter.c	3.5	07/11/80	*/

#include "../h/param.h"
#include "../h/systm.h"
#include "../h/seg.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/proc.h"
#include "../h/text.h"
#include "../h/vm.h"
#include "../h/cmap.h"

int	maxpgio = MAXPGIO;
int	maxslp = MAXSLP;
int	minfree = MINFREE;
int	desfree = DESFREE;
int	lotsfree = 0;		/* set to LOTSFREE in main unless adbed */
int	saferss = SAFERSS;
int	slowscan = SLOWSCAN;
int	fastscan = FASTSCAN;
int	klin = KLIN;
int	klout = KLOUT;
int	multprog = -1;		/* so we don't count process 2 */

double	avenrun[3];		/* load average, of runnable procs */

/*
 * The main loop of the scheduling (swapping) process.
 *
 * The basic idea is:
 *	see if anyone wants to be swapped in;
 *	swap out processes until there is room;
 *	swap him in;
 *	repeat.
 * If the paging rate is too high, or the average free memory
 * is very low, then we do not consider swapping anyone in,
 * but rather look for someone to swap out.
 *
 * The runout flag is set whenever someone is swapped out.
 * Sched sleeps on it awaiting work.
 *
 * Sched sleeps on runin whenever it cannot find enough
 * core (by swapping out or otherwise) to fit the
 * selected swapped process.  It is awakened when the
 * core situation changes and in any case once per second.
 *
 * sched DOESN'T ACCOUNT FOR PAGE TABLE SIZE IN CALCULATIONS.
 */

#define	swappable(p) \
	(((p)->p_flag&(SSYS|SLOCK|SULOCK|SLOAD|SPAGE|SKEEP|SWEXIT|SPHYSIO))==SLOAD)

/* insure non-zero */
#define	nz(x)	(x != 0 ? x : 1)

#define	NBIG	4
#define	MAXNBIG	10
int	nbig = NBIG;

struct bigp {
	struct	proc *bp_proc;
	int	bp_pri;
	struct	bigp *bp_link;
} bigp[MAXNBIG], bplist;

sched()
{
	register struct proc *rp, *p, *inp;
	int outpri, inpri, rppri;
	int sleeper, desparate, deservin, needs, divisor;
	register struct bigp *bp, *nbp;
	int biggot, gives;

	/*
	 * Check if paging rate is too high, or average of
	 * free list very low and if so, adjust multiprogramming
	 * load by swapping someone out.
	 *
	 * Avoid glitches: don't hard swap the only process,
	 * and don't swap based on paging rate if there is a reasonable
	 * amount of free memory.
	 */
loop:
	(void) spl6();
	deservin = 0;
	sleeper = 0;
	p = 0;
	if (kmapwnt || (multprog > 1 && avefree < desfree &&
	    (rate.v_pgin + rate.v_pgout > maxpgio || avefree < minfree))) {
		desparate = 1;
		goto hardswap;
	}
	desparate = 0;
	/*
	 * Not desparate for core,
	 * look for someone who deserves to be brought in.
	 */
	outpri = -20000;
	for (rp = &proc[0]; rp < &proc[NPROC]; rp++) switch(rp->p_stat) {

	case SRUN:
		if ((rp->p_flag&SLOAD) == 0) {
			rppri = rp->p_time - rp->p_swrss / nz((maxpgio/2) * CLSIZE) +
			    rp->p_slptime - (rp->p_nice-NZERO)*8;
			if (rppri > outpri) {
				if (rp->p_poip)
					continue;
				if (rp->p_textp && rp->p_textp->x_poip)
					continue;
				p = rp;
				outpri = rppri;
			}
		}
		continue;

	case SSLEEP:
	case SSTOP:
		if ((freemem < desfree || rp->p_rssize == 0) &&
		    rp->p_slptime > maxslp &&
		    (!rp->p_textp || (rp->p_textp->x_flag&XLOCK)==0) &&
		    swappable(rp)) {
			/*
			 * Kick out deadwood.
			 * FOLLOWING 3 LINES MUST BE AT spl6().
			 */
			rp->p_flag &= ~SLOAD;
			if (rp->p_stat == SRUN)
				remrq(rp);
			(void) swapout(rp, rp->p_dsize, rp->p_ssize);
			goto loop;
		}
		continue;
	}

	/*
	 * No one wants in, so nothing to do.
	 */
	if (outpri == -20000) {
		runout++;
		sleep((caddr_t)&runout, PSWP);
		goto loop;
	}
	(void) spl0();
	/*
	 * Decide how deserving this guy is.  If he is deserving
	 * we will be willing to work harder to bring him in.
	 * Needs is an estimate of how much core he will need.
	 * If he has been out for a while, then we will
	 * bring him in with 1/2 the core he will need, otherwise
	 * we are conservative.
	 */
	deservin = 0;
	divisor = 1;
	if (outpri > maxslp/2) {
		deservin = 1;
		divisor = 2;
	}
	needs = p->p_swrss;
	if (p->p_textp && p->p_textp->x_ccount == 0)
		needs += p->p_textp->x_swrss;
	if (freemem - deficit > needs / divisor) {
		deficit += needs;
		if (swapin(p))
			goto loop;
		deficit -= imin(needs, deficit);
	}

hardswap:
	/*
	 * Need resources (kernel map or memory), swap someone out.
	 * Select the nbig largest jobs, then the oldest of these
	 * is ``most likely to get booted.''
	 */
	(void) spl6();
	inp = p;
	sleeper = 0;
	if (nbig > MAXNBIG)
		nbig = MAXNBIG;
	if (nbig < 1)
		nbig = 1;
	biggot = 0;
	bplist.bp_link = 0;
	for (rp = &proc[0]; rp < &proc[NPROC]; rp++) {
		if (!swappable(rp))
			continue;
		if (rp->p_stat==SZOMB)
			continue;
		if (rp == inp)
			continue;
		if (rp->p_textp && rp->p_textp->x_flag&XLOCK)
			continue;
		if (rp->p_slptime > maxslp &&
		    (rp->p_stat==SSLEEP&&rp->p_pri>PZERO||rp->p_stat==SSTOP)) {
			if (sleeper < rp->p_slptime) {
				p = rp;
				sleeper = rp->p_slptime;
			}
		} else if (!sleeper && (rp->p_stat==SRUN||rp->p_stat==SSLEEP)) {
			rppri = rp->p_rssize;
			if (rp->p_textp)
				rppri += rp->p_textp->x_rssize/rp->p_textp->x_ccount;
			if (biggot < nbig)
				nbp = &bigp[biggot++];
			else {
				nbp = bplist.bp_link;
				if (nbp->bp_pri > rppri)
					continue;
				bplist.bp_link = nbp->bp_link;
			}
			for (bp = &bplist; bp->bp_link; bp = bp->bp_link)
				if (rppri < bp->bp_link->bp_pri)
					break;
			nbp->bp_link = bp->bp_link;
			bp->bp_link = nbp;
			nbp->bp_pri = rppri;
			nbp->bp_proc = rp;
		}
	}
	if (!sleeper) {
		p = NULL;
		inpri = -1000;
		for (bp = bplist.bp_link; bp; bp = bp->bp_link) {
			rp = bp->bp_proc;
			rppri = rp->p_time+rp->p_nice-NZERO;
			if (rppri >= inpri) {
				p = rp;
				inpri = rppri;
			}
		}
	}
	/*
	 * If we found a long-time sleeper, or we are desparate and
	 * found anyone to swap out, or if someone deserves to come
	 * in and we didn't find a sleeper, but found someone who
	 * has been in core for a reasonable length of time, then
	 * we kick the poor luser out.
	 */
	if (sleeper || desparate && p || deservin && inpri > maxslp) {
		p->p_flag &= ~SLOAD;
		if (p->p_stat == SRUN)
			remrq(p);
		if (desparate) {
			/*
			 * Want to give this space to the rest of
			 * the processes in core so give them a chance
			 * by increasing the deficit.
			 */
			gives = p->p_rssize;
			if (p->p_textp)
				gives += p->p_textp->x_rssize / p->p_textp->x_ccount;
			deficit += gives;
		} else
			gives = 0;	/* someone else taketh away */
		if (swapout(p, p->p_dsize, p->p_ssize) == 0)
			deficit -= imin(gives, deficit);
		goto loop;
	}
	/*
	 * Want to swap someone in, but can't
	 * so wait on runin.
	 */
	(void) spl6();
	runin++;
	sleep((caddr_t)&runin, PSWP);
	goto loop;
}

vmmeter()
{
	register unsigned *cp, *rp, *sp;

	deficit -= imin(deficit, imax(deficit / 10, maxpgio / 2));
	ave(avefree, freemem, 5);
	/* v_pgin is maintained by clock.c */
	cp = &cnt.v_first; rp = &rate.v_first; sp = &sum.v_first;
	while (cp <= &cnt.v_last) {
		ave(*rp, *cp, 5);
		*sp += *cp;
		*cp = 0;
		rp++, cp++, sp++;
	}
	if (time % 5 == 0) {
		vmtotal();
		rate.v_swpin = cnt.v_swpin;
		sum.v_swpin += cnt.v_swpin;
		cnt.v_swpin = 0;
		rate.v_swpout = cnt.v_swpout;
		sum.v_swpout += cnt.v_swpout;
		cnt.v_swpout = 0;
	}
	if (avefree < minfree && runout || proc[0].p_slptime > maxslp/2) {
		runout = 0;
		runin = 0;
		wakeup((caddr_t)&runin);
		wakeup((caddr_t)&runout);
	}
}

vmpago()
{
	register int vavail;
	register int scanrate;

	/*
	 * Compute new rate for clock; if
	 * nonzero, restart clock.
	 * Rate ranges linearly from one rev per
	 * slowscan seconds when there is lotsfree memory
	 * available to one rev per fastscan seconds when
	 * there is no memory available.
	 */
	nscan = desscan = 0;
	vavail = freemem - deficit;
	if (vavail < 0)
		vavail = 0;
	if (freemem >= lotsfree)
		return;
	scanrate = (slowscan * vavail + fastscan * (lotsfree - vavail)) / nz(lotsfree);
	desscan = LOOPSIZ / nz(scanrate);
	/*
	 * DIVIDE BY 4 TO ACCOUNT FOR RUNNING 4* A SECOND (see clock.c)
	 */
	desscan /= 4;
	wakeup((caddr_t)&proc[2]);
}

vmtotal()
{
	register struct proc *p;
	register struct text *xp;
	int nrun = 0;

	total.t_vmtxt = 0;
	total.t_avmtxt = 0;
	total.t_rmtxt = 0;
	total.t_armtxt = 0;
	for (xp = &text[0]; xp < &text[NTEXT]; xp++)
		if (xp->x_iptr) {
			total.t_vmtxt += xp->x_size;
			total.t_rmtxt += xp->x_rssize;
			for (p = xp->x_caddr; p; p = p->p_xlink)
			switch (p->p_stat) {

			case SSTOP:
			case SSLEEP:
				if (p->p_slptime >= maxslp)
					continue;
				/* fall into... */

			case SRUN:
			case SIDL:
				total.t_avmtxt += xp->x_size;
				total.t_armtxt += xp->x_rssize;
				goto next;
			}
next:
			;
		}
	total.t_vm = 0;
	total.t_avm = 0;
	total.t_rm = 0;
	total.t_arm = 0;
	total.t_rq = 0;
	total.t_dw = 0;
	total.t_pw = 0;
	total.t_sl = 0;
	total.t_sw = 0;
	for (p = &proc[0]; p < &proc[NPROC]; p++) {
		if (p->p_flag & SSYS)
			continue;
		if (p->p_stat) {
			total.t_vm += p->p_dsize + p->p_ssize;
			total.t_rm += p->p_rssize;
			switch (p->p_stat) {

			case SSLEEP:
			case SSTOP:
				if (p->p_pri <= PZERO)
					nrun++;
				if (p->p_flag & SPAGE)
					total.t_pw++;
				else if (p->p_flag & SLOAD) {
					if (p->p_pri <= PZERO)
						total.t_dw++;
					else if (p->p_slptime < maxslp)
						total.t_sl++;
				} else if (p->p_slptime < maxslp)
					total.t_sw++;
				if (p->p_slptime < maxslp)
					goto active;
				break;

			case SRUN:
			case SIDL:
				nrun++;
				if (p->p_flag & SLOAD)
					total.t_rq++;
				else
					total.t_sw++;
active:
				total.t_avm += p->p_dsize + p->p_ssize;
				total.t_arm += p->p_rssize;
				break;
			}
		}
	}
	total.t_vm += total.t_vmtxt;
	total.t_avm += total.t_avmtxt;
	total.t_rm += total.t_rmtxt;
	total.t_arm += total.t_armtxt;
	total.t_free = avefree;
	loadav(avenrun, nrun);
}

/*
 * Constants for averages over 1, 5, and 15 minutes
 * when sampling at 5 second intervals.
 */
double	cexp[3] = {
	0.9200444146293232,	/* exp(-1/12) */
	0.9834714538216174,	/* exp(-1/60) */
	0.9944598480048967,	/* exp(-1/180) */
};

/*
 * Compute a tenex style load average of a quantity on
 * 1, 5 and 15 minute intervals.
 */
loadav(avg, n)
	register double *avg;
	int n;
{
	register int i;

	for (i = 0; i < 3; i++)
		avg[i] = cexp[i] * avg[i] + n * (1.0 - cexp[i]);
}