harvey/sys/src/9/port/proc.c

#include	"u.h"
#include	"../port/lib.h"
#include	"mem.h"
#include	"dat.h"
#include	"fns.h"
#include	"../port/error.h"

int	nrdy;
Ref	noteidalloc;

long	delayedscheds;	/* statistics */

static Ref	pidalloc;

static struct Procalloc
{
	Lock;
	Proc*	ht[128];
	Proc*	arena;
	Proc*	free;
} procalloc;

enum
{
	Q=(HZ/20)*4,
	DQ=((HZ-Q)/40)*2,
};

static Schedq	runq[Nrq];
static ulong	runvec;
static int	quanta[Nrq] =
{
	Q+19*DQ, Q+18*DQ, Q+17*DQ, Q+16*DQ,
	Q+15*DQ, Q+14*DQ, Q+13*DQ, Q+12*DQ,
	Q+11*DQ, Q+10*DQ, Q+ 9*DQ, Q+ 8*DQ,
	Q+ 7*DQ, Q+ 6*DQ, Q+ 5*DQ, Q+ 4*DQ,
	Q+ 3*DQ, Q+ 2*DQ, Q+ 1*DQ, Q+ 0*DQ,
};

extern Edfinterface	nulledf;

Edfinterface *edf = &nulledf;

char *statename[] =
{	/* BUG: generate automatically */
	"Dead",
	"Moribund",
	"Ready",
	"Scheding",
	"Running",
	"Queueing",
	"QueueingR",
	"QueueingW",
	"Wakeme",
	"Broken",
	"Stopped",
	"Rendez",
	"Released",
};

static void pidhash(Proc*);
static void pidunhash(Proc*);

/*
 * Always splhi()'ed.
 */
void
schedinit(void)		/* never returns */
{
	setlabel(&m->sched);
	if(up) {
		m->proc = 0;
		switch(up->state) {
		case Running:
			ready(up);
			break;
		case Moribund:
			up->state = Dead;
			if (edf->isedf(up))
				edf->edfbury(up);

			/*
			 * Holding locks from pexit:
			 * 	procalloc
			 *	palloc
			 */
			mmurelease(up);

			up->qnext = procalloc.free;
			procalloc.free = up;

			unlock(&palloc);
			unlock(&procalloc);
			break;
		}
		up->mach = 0;
		up = nil;
	}
	sched();
}

/*
 *  If changing this routine, look also at sleep().  It
 *  contains a copy of the guts of sched().
 */
void
sched(void)
{
	int x[1];

	if(m->ilockdepth)
		panic("ilockdepth %d, last lock 0x%p at 0x%lux, sched called from 0x%lux",
			m->ilockdepth, up?up->lastilock:nil,
			(up && up->lastilock)?up->lastilock->pc:0, getcallerpc(x+3));

	if(up){
		if(up->nlocks && up->state != Moribund){
 			delayedscheds++;
			return;
		}

		splhi();

		/* statistics */
		m->cs++;

		procsave(up);
		if(setlabel(&up->sched)){
			procrestore(up);
			spllo();
			return;
		}
		gotolabel(&m->sched);
	}
	up = runproc();
	up->state = Running;
	up->mach = MACHP(m->machno);
	m->proc = up;
	mmuswitch(up);
	gotolabel(&up->sched);
}

int
anyready(void)
{
	return runvec || edf->edfanyready();
}

int
anyhigher(void)
{
	return runvec & ~((1<<(up->priority+1))-1);
}

/*
 *  here once per clock tick to see if we should resched
 */
void
hzsched(void)
{
	/* another cycle, another quantum */
	up->quanta--;

	/* edf scheduler always gets first chance */
	if(edf->isedf(up))
		return;

	/* don't bother unless someone is elegible */
	if(anyhigher() || (!up->fixedpri && anyready())){
		sched();
		splhi();
	}
}

/*
 *  here at the end of non-clock interrupts to see if we should preempt the
 *  current process.  Returns 1 if preempted, 0 otherwise.
 */
int
preempted(void)
{
	if(up && up->state == Running)
	if(up->preempted == 0)
	if(anyhigher())
	if(!active.exiting){
		up->preempted = 1;
		sched();
		splhi();
		up->preempted = 0;
		return 1;
	}
	return 0;
}

/*
 *  ready(p) picks a new priority for a process and sticks it in the
 *  runq for that priority.
 *
 *  - fixed priority processes never move
 *  - a process that uses all its quanta before blocking goes down a
 *    priority level
 *  - a process that uses less than half its quanta before blocking
 *    goes up a priority level
 *  - a process that blocks after using up half or more of it's quanta
 *    stays at the same level
 *
 *  new quanta are assigned each time a process blocks or changes level
 */
void
ready(Proc *p)
{
	int s, pri;
	Schedq *rq;

	s = splhi();

	if(edf->isedf(p)){
		edf->edfready(p);
		splx(s);
		return;
	}

	pri = p->priority;

	if(p->fixedpri){
		pri = p->basepri;
		p->quanta = HZ;
	} else if(p->state == Running){
		if(p->quanta <= 0){
			/* degrade priority of anyone that used their whole quanta */
			if(pri > 0)
				pri--;
			p->quanta = quanta[pri];
		}
	} else {
		if(p->quanta > quanta[pri]/2){
			/* blocked before using half its quanta, go up */
			if(++pri > p->basepri)
				pri = p->basepri;
		}
		p->quanta = quanta[pri];
	}

	rq = &runq[pri];
	p->priority = pri;
	lock(runq);
	p->rnext = 0;
	if(rq->tail)
		rq->tail->rnext = p;
	else
		rq->head = p;
	rq->tail = p;
	rq->n++;
	nrdy++;
	runvec |= 1<<pri;
	p->readytime = m->ticks;
	p->state = Ready;
	unlock(runq);
	splx(s);
}

Proc*
runproc(void)
{
	Schedq *rq;
	Proc *p, *l, *tp;
	ulong start, now;
	int i;

	start = perfticks();

	if ((p = edf->edfrunproc()) != nil)
		return p;

loop:
	/*
	 *  find a process that last ran on this processor (affinity),
	 *  or one that hasn't moved in a while (load balancing).  Every
	 *  time around the loop affinity goes down.
	 */
	spllo();
	for(i = 0;; i++){
		/*
		 *  find the highest priority target process that this
		 *  processor can run given affinity constraints
		 */
		for(rq = &runq[Nrq-1]; rq >= runq; rq--){
			tp = rq->head;
			if(tp == 0)
				continue;
			for(; tp; tp = tp->rnext){
				if(tp->mp == nil || tp->mp == MACHP(m->machno)
				|| (!tp->wired && i > 0))
					goto found;
			}
		}

		/* waste time or halt the CPU */
		idlehands();

		/* remember how much time we're here */
		now = perfticks();
		m->perf.inidle += now-start;
		start = now;
	}

found:
	splhi();
	if(!canlock(runq))
		goto loop;

	/*
	 *  the queue may have changed before we locked runq,
	 *  refind the target process.
	 */
	l = 0;
	for(p = rq->head; p; p = p->rnext){
		if(p == tp)
			break;
		l = p;
	}

	/*
	 *  p->mach==0 only when process state is saved
	 */
	if(p == 0 || p->mach){
		unlock(runq);
		goto loop;
	}
	if(p->rnext == 0)
		rq->tail = l;
	if(l)
		l->rnext = p->rnext;
	else
		rq->head = p->rnext;
	if(rq->head == nil)
		runvec &= ~(1<<(rq-runq));
	rq->n--;
	nrdy--;
	if(p->state != Ready)
		print("runproc %s %lud %s\n", p->text, p->pid, statename[p->state]);
	unlock(runq);

	p->state = Scheding;
	p->mp = MACHP(m->machno);

	return p;
}

int
canpage(Proc *p)
{
	int ok = 0;

	splhi();
	lock(runq);
	/* Only reliable way to see if we are Running */
	if(p->mach == 0) {
		p->newtlb = 1;
		ok = 1;
	}
	unlock(runq);
	spllo();

	return ok;
}

Proc*
newproc(void)
{
	Proc *p;

	lock(&procalloc);
	for(;;) {
		if(p = procalloc.free)
			break;

		unlock(&procalloc);
		resrcwait("no procs");
		lock(&procalloc);
	}
	procalloc.free = p->qnext;
	unlock(&procalloc);

	p->state = Scheding;
	p->psstate = "New";
	p->mach = 0;
	p->qnext = 0;
	p->nchild = 0;
	p->nwait = 0;
	p->waitq = 0;
	p->parent = 0;
	p->pgrp = 0;
	p->egrp = 0;
	p->fgrp = 0;
	p->rgrp = 0;
	p->pdbg = 0;
	p->fpstate = FPinit;
	p->kp = 0;
	p->procctl = 0;
	p->notepending = 0;
	p->ureg = 0;
	p->privatemem = 0;
	p->noswap = 0;
	p->errstr = p->errbuf0;
	p->syserrstr = p->errbuf1;
	p->errbuf0[0] = '\0';
	p->errbuf1[0] = '\0';
	p->nlocks = 0;
	p->delaysched = 0;
	kstrdup(&p->user, "*nouser");
	kstrdup(&p->text, "*notext");
	kstrdup(&p->args, "");
	p->nargs = 0;
	p->setargs = 0;
	memset(p->seg, 0, sizeof p->seg);
	p->pid = incref(&pidalloc);
	pidhash(p);
	p->noteid = incref(&noteidalloc);
	if(p->pid==0 || p->noteid==0)
		panic("pidalloc");
	if(p->kstack == 0)
		p->kstack = smalloc(KSTACK);

	/* sched params */
	p->mp = 0;
	p->wired = 0;
	procpriority(p, PriNormal, 0);

	p->task = nil;

	return p;
}

/*
 * wire this proc to a machine
 */
void
procwired(Proc *p, int bm)
{
	Proc *pp;
	int i;
	char nwired[MAXMACH];
	Mach *wm;

	if(bm < 0){
		/* pick a machine to wire to */
		memset(nwired, 0, sizeof(nwired));
		p->wired = 0;
		pp = proctab(0);
		for(i=0; i<conf.nproc; i++, pp++){
			wm = pp->wired;
			if(wm && pp->pid)
				nwired[wm->machno]++;
		}
		bm = 0;
		for(i=0; i<conf.nmach; i++)
			if(nwired[i] < nwired[bm])
				bm = i;
	} else {
		/* use the virtual machine requested */
		bm = bm % conf.nmach;
	}

	p->wired = MACHP(bm);
	p->mp = p->wired;
}

void
procpriority(Proc *p, int pri, int fixed)
{
	if(pri >= Nrq)
		pri = Nrq - 1;
	else if(pri < 0)
		pri = 0;
	p->basepri = pri;
	p->priority = pri;
	if(fixed){
		p->quanta = 0xfffff;
		p->fixedpri = 1;
	} else {
		p->quanta = quanta[pri];
		p->fixedpri = 0;
	}
}

void
procinit0(void)		/* bad planning - clashes with devproc.c */
{
	Proc *p;
	int i;

	procalloc.free = xalloc(conf.nproc*sizeof(Proc));
	if(procalloc.free == nil)
		panic("cannot allocate %lud procs\n", conf.nproc);
	procalloc.arena = procalloc.free;

	p = procalloc.free;
	for(i=0; i<conf.nproc-1; i++,p++)
		p->qnext = p+1;
	p->qnext = 0;
}

/*
 *  sleep if a condition is not true.  Another process will
 *  awaken us after it sets the condition.  When we awaken
 *  the condition may no longer be true.
 *
 *  we lock both the process and the rendezvous to keep r->p
 *  and p->r synchronized.
 */
void
sleep(Rendez *r, int (*f)(void*), void *arg)
{
	int s;

	s = splhi();

	if (up->nlocks)
		print("process %lud sleeps with %lud locks held, last lock 0x%p locked at pc 0x%lux\n",
			up->pid, up->nlocks, up->lastlock, up->lastlock->pc);
	lock(r);
	lock(&up->rlock);
	if(r->p){
		print("double sleep %lud %lud\n", r->p->pid, up->pid);
		dumpstack();
	}

	/*
	 *  Wakeup only knows there may be something to do by testing
	 *  r->p in order to get something to lock on.
	 *  Flush that information out to memory in case the sleep is
	 *  committed.
	 */
	r->p = up;

	if((*f)(arg) || up->notepending){
		/*
		 *  if condition happened or a note is pending
		 *  never mind
		 */
		r->p = nil;
		unlock(&up->rlock);
		unlock(r);
	} else {
		/*
		 *  now we are committed to
		 *  change state and call scheduler
		 */
		up->state = Wakeme;
		up->r = r;

		/* statistics */
		m->cs++;

		procsave(up);
		if(setlabel(&up->sched)) {
			/*
			 *  here when the process is awakened
			 */
			procrestore(up);
			spllo();
		} else {
			/*
			 *  here to go to sleep (i.e. stop Running)
			 */
			unlock(&up->rlock);
			unlock(r);
			// Behind unlock, we may call wakeup on ourselves.

			if (edf->isedf(up))
				edf->edfblock(up);

			gotolabel(&m->sched);
		}
	}

	if(up->notepending) {
		up->notepending = 0;
		splx(s);
		error(Eintr);
	}

	splx(s);
}

int
tfn(void *arg)
{
	return MACHP(0)->ticks >= up->twhen || up->tfn(arg);
}

void
tsleep(Rendez *r, int (*fn)(void*), void *arg, int ms)
{
	ulong when;
	Proc *f, **l;

	when = ms2tk(ms) + MACHP(0)->ticks;

	lock(&talarm);
	/* take out of list if checkalarm didn't */
	if(up->trend) {
		l = &talarm.list;
		for(f = *l; f; f = f->tlink) {
			if(f == up) {
				*l = up->tlink;
				break;
			}
			l = &f->tlink;
		}
	}
	/* insert in increasing time order */
	l = &talarm.list;
	for(f = *l; f; f = f->tlink) {
		if(f->twhen >= when)
			break;
		l = &f->tlink;
	}
	up->trend = r;
	up->twhen = when;
	up->tfn = fn;
	up->tlink = *l;
	*l = up;
	unlock(&talarm);

	if(waserror()){
		up->twhen = 0;
		nexterror();
	}
	sleep(r, tfn, arg);
	up->twhen = 0;
	poperror();
}

/*
 *  Expects that only one process can call wakeup for any given Rendez.
 *  We hold both locks to ensure that r->p and p->r remain consistent.
 *  Richard Miller has a better solution that doesn't require both to
 *  be held simultaneously, but I'm a paranoid - presotto.
 */
Proc*
wakeup(Rendez *r)
{
	Proc *p;
	int s;

	s = splhi();

	lock(r);
	p = r->p;

	if(p != nil){
		lock(&p->rlock);
		if(p->state != Wakeme || p->r != r)
			panic("wakeup: state");
		r->p = nil;
		p->r = nil;
		ready(p);
		unlock(&p->rlock);
	}
	unlock(r);

	splx(s);

	return p;
}

/*
 *  if waking a sleeping process, this routine must hold both
 *  p->rlock and r->lock.  However, it can't know them in
 *  the same order as wakeup causing a possible lock ordering
 *  deadlock.  We break the deadlock by giving up the p->rlock
 *  lock if we can't get the r->lock and retrying.
 */
int
postnote(Proc *p, int dolock, char *n, int flag)
{
	int s, ret;
	Rendez *r;
	Proc *d, **l;

	if(dolock)
		qlock(&p->debug);

	if(flag != NUser && (p->notify == 0 || p->notified))
		p->nnote = 0;

	ret = 0;
	if(p->nnote < NNOTE) {
		strcpy(p->note[p->nnote].msg, n);
		p->note[p->nnote++].flag = flag;
		ret = 1;
	}
	p->notepending = 1;
	if(dolock)
		qunlock(&p->debug);

	/* this loop is to avoid lock ordering problems. */
	for(;;){
		s = splhi();
		lock(&p->rlock);
		r = p->r;

		/* waiting for a wakeup? */
		if(r == nil)
			break;	/* no */

		/* try for the second lock */
		if(canlock(r)){
			if(p->state != Wakeme || r->p != p)
				panic("postnote: state %d %d %d", r->p != p, p->r != r, p->state);
			p->r = nil;
			r->p = nil;
			ready(p);
			unlock(r);
			break;
		}

		/* give other process time to get out of critical section and try again */
		unlock(&p->rlock);
		splx(s);
		sched();
	}
	unlock(&p->rlock);
	splx(s);

	if(p->state != Rendezvous)
		return ret;

	/* Try and pull out of a rendezvous */
	lock(p->rgrp);
	if(p->state == Rendezvous) {
		p->rendval = ~0;
		l = &REND(p->rgrp, p->rendtag);
		for(d = *l; d; d = d->rendhash) {
			if(d == p) {
				*l = p->rendhash;
				break;
			}
			l = &d->rendhash;
		}
		ready(p);
	}
	unlock(p->rgrp);
	return ret;
}

/*
 * weird thing: keep at most NBROKEN around
 */
#define	NBROKEN 4
struct
{
	QLock;
	int	n;
	Proc	*p[NBROKEN];
}broken;

void
addbroken(Proc *p)
{
	qlock(&broken);
	if(broken.n == NBROKEN) {
		ready(broken.p[0]);
		memmove(&broken.p[0], &broken.p[1], sizeof(Proc*)*(NBROKEN-1));
		--broken.n;
	}
	broken.p[broken.n++] = p;
	qunlock(&broken);

	if (edf->isedf(up))
		edf->edfbury(up);
	p->state = Broken;
	p->psstate = 0;
	sched();
}

void
unbreak(Proc *p)
{
	int b;

	qlock(&broken);
	for(b=0; b < broken.n; b++)
		if(broken.p[b] == p) {
			broken.n--;
			memmove(&broken.p[b], &broken.p[b+1],
					sizeof(Proc*)*(NBROKEN-(b+1)));
			ready(p);
			break;
		}
	qunlock(&broken);
}

int
freebroken(void)
{
	int i, n;

	qlock(&broken);
	n = broken.n;
	for(i=0; i<n; i++) {
		ready(broken.p[i]);
		broken.p[i] = 0;
	}
	broken.n = 0;
	qunlock(&broken);
	return n;
}

void
pexit(char *exitstr, int freemem)
{
	Proc *p;
	Segment **s, **es;
	long utime, stime;
	Waitq *wq, *f, *next;
	Fgrp *fgrp;
	Egrp *egrp;
	Rgrp *rgrp;
	Pgrp *pgrp;
	Chan *dot;

	up->alarm = 0;

	/* nil out all the resources under lock (free later) */
	qlock(&up->debug);
	fgrp = up->fgrp;
	up->fgrp = nil;
	egrp = up->egrp;
	up->egrp = nil;
	rgrp = up->rgrp;
	up->rgrp = nil;
	pgrp = up->pgrp;
	up->pgrp = nil;
	dot = up->dot;
	up->dot = nil;
	qunlock(&up->debug);

	if(fgrp)
		closefgrp(fgrp);
	if(egrp)
		closeegrp(egrp);
	if(rgrp)
		closergrp(rgrp);
	if(dot)
		cclose(dot);
	if(pgrp)
		closepgrp(pgrp);

	/*
	 * if not a kernel process and have a parent,
	 * do some housekeeping.
	 */
	if(up->kp == 0) {
		p = up->parent;
		if(p == 0) {
			if(exitstr == 0)
				exitstr = "unknown";
			panic("boot process died: %s", exitstr);
		}

		while(waserror())
			;

		wq = smalloc(sizeof(Waitq));
		poperror();

		wq->w.pid = up->pid;
		utime = up->time[TUser] + up->time[TCUser];
		stime = up->time[TSys] + up->time[TCSys];
		wq->w.time[TUser] = tk2ms(utime);
		wq->w.time[TSys] = tk2ms(stime);
		wq->w.time[TReal] = tk2ms(MACHP(0)->ticks - up->time[TReal]);
		if(exitstr && exitstr[0])
			snprint(wq->w.msg, sizeof(wq->w.msg), "%s %lud: %s", up->text, up->pid, exitstr);
		else
			wq->w.msg[0] = '\0';

		lock(&p->exl);
		/*
		 *  If my parent is no longer alive, or if there would be more
		 *  than 128 zombie child processes for my parent, then don't
		 *  leave a wait record behind.  This helps prevent badly
		 *  written daemon processes from accumulating lots of wait
		 *  records.
		 */
		if(p->pid == up->parentpid && p->state != Broken && p->nwait < 128) {
			p->nchild--;
			p->time[TCUser] += utime;
			p->time[TCSys] += stime;

			wq->next = p->waitq;
			p->waitq = wq;
			p->nwait++;

			wakeup(&p->waitr);
			unlock(&p->exl);
		}
		else {
			unlock(&p->exl);
			free(wq);
		}
	}

	if(!freemem)
		addbroken(up);

	qlock(&up->seglock);
	es = &up->seg[NSEG];
	for(s = up->seg; s < es; s++) {
		if(*s) {
			putseg(*s);
			*s = 0;
		}
	}
	qunlock(&up->seglock);

	lock(&up->exl);		/* Prevent my children from leaving waits */
	pidunhash(up);
	up->pid = 0;
	wakeup(&up->waitr);
	unlock(&up->exl);

	for(f = up->waitq; f; f = next) {
		next = f->next;
		free(f);
	}

	/* release debuggers */
	qlock(&up->debug);
	if(up->pdbg) {
		wakeup(&up->pdbg->sleep);
		up->pdbg = 0;
	}
	qunlock(&up->debug);

	/* Sched must not loop for these locks */
	lock(&procalloc);
	lock(&palloc);

	if (edf->isedf(up))
		edf->edfbury(up);
	up->state = Moribund;
	sched();
	panic("pexit");
}

int
haswaitq(void *x)
{
	Proc *p;

	p = (Proc *)x;
	return p->waitq != 0;
}

ulong
pwait(Waitmsg *w)
{
	ulong cpid;
	Waitq *wq;

	if(!canqlock(&up->qwaitr))
		error(Einuse);

	if(waserror()) {
		qunlock(&up->qwaitr);
		nexterror();
	}

	lock(&up->exl);
	if(up->nchild == 0 && up->waitq == 0) {
		unlock(&up->exl);
		error(Enochild);
	}
	unlock(&up->exl);

	sleep(&up->waitr, haswaitq, up);

	lock(&up->exl);
	wq = up->waitq;
	up->waitq = wq->next;
	up->nwait--;
	unlock(&up->exl);

	qunlock(&up->qwaitr);
	poperror();

	if(w)
		memmove(w, &wq->w, sizeof(Waitmsg));
	cpid = wq->w.pid;
	free(wq);
	return cpid;
}

Proc*
proctab(int i)
{
	return &procalloc.arena[i];
}

void
dumpaproc(Proc *p)
{
	ulong bss;
	char *s;

	if(p == 0)
		return;

	bss = 0;
	if(p->seg[BSEG])
		bss = p->seg[BSEG]->top;

	s = p->psstate;
	if(s == 0)
		s = statename[p->state];
	print("%3lud:%10s pc %8lux dbgpc %8lux  %8s (%s) ut %ld st %ld bss %lux qpc %lux nl %lud nd %lud lpc %lux pri %lud\n",
		p->pid, p->text, p->pc, dbgpc(p),  s, statename[p->state],
		p->time[0], p->time[1], bss, p->qpc, p->nlocks, p->delaysched, p->lastlock ? p->lastlock->pc : 0, p->priority);
}

void
procdump(void)
{
	int i;
	Proc *p;

	if(up)
		print("up %lud\n", up->pid);
	else
		print("no current process\n");
	for(i=0; i<conf.nproc; i++) {
		p = &procalloc.arena[i];
		if(p->state == Dead)
			continue;

		dumpaproc(p);
	}
}

/*
 *  wait till all processes have flushed their mmu
 *  state about segement s
 */
void
procflushseg(Segment *s)
{
	int i, ns, nm, nwait;
	Proc *p;

	/*
	 *  tell all processes with this
	 *  segment to flush their mmu's
	 */
	nwait = 0;
	for(i=0; i<conf.nproc; i++) {
		p = &procalloc.arena[i];
		if(p->state == Dead)
			continue;
		for(ns = 0; ns < NSEG; ns++)
			if(p->seg[ns] == s){
				p->newtlb = 1;
				for(nm = 0; nm < conf.nmach; nm++){
					if(MACHP(nm)->proc == p){
						MACHP(nm)->flushmmu = 1;
						nwait++;
					}
				}
				break;
			}
	}

	if(nwait == 0)
		return;

	/*
	 *  wait for all processors to take a clock interrupt
	 *  and flush their mmu's
	 */
	for(nm = 0; nm < conf.nmach; nm++)
		if(MACHP(nm) != m)
			while(MACHP(nm)->flushmmu)
				sched();
}

void
scheddump(void)
{
	Proc *p;
	Schedq *rq;

	for(rq = &runq[Nrq-1]; rq >= runq; rq--){
		if(rq->head == 0)
			continue;
		print("rq%ld:", rq-runq);
		for(p = rq->head; p; p = p->rnext)
			print(" %lud(%lud)", p->pid, m->ticks - p->readytime);
		print("\n");
		delay(150);
	}
	print("nrdy %d\n", nrdy);
}

void
kproc(char *name, void (*func)(void *), void *arg)
{
	Proc *p;
	static Pgrp *kpgrp;

	p = newproc();
	p->psstate = 0;
	p->procmode = 0640;
	p->kp = 1;
	p->noswap = 1;

	p->fpsave = up->fpsave;
	p->scallnr = up->scallnr;
	p->s = up->s;
	p->nerrlab = 0;
	p->slash = up->slash;
	p->dot = up->dot;
	incref(p->dot);

	memmove(p->note, up->note, sizeof(p->note));
	p->nnote = up->nnote;
	p->notified = 0;
	p->lastnote = up->lastnote;
	p->notify = up->notify;
	p->ureg = 0;
	p->dbgreg = 0;

	procpriority(p, PriKproc, 0);

	kprocchild(p, func, arg);

	kstrdup(&p->user, eve);
	kstrdup(&p->text, name);
	if(kpgrp == 0)
		kpgrp = newpgrp();
	p->pgrp = kpgrp;
	incref(kpgrp);

	memset(p->time, 0, sizeof(p->time));
	p->time[TReal] = MACHP(0)->ticks;
	ready(p);
	/*
	 *  since the bss/data segments are now shareable,
	 *  any mmu info about this process is now stale
	 *  and has to be discarded.
	 */
	p->newtlb = 1;
	flushmmu();
}

/*
 *  called splhi() by notify().  See comment in notify for the
 *  reasoning.
 */
void
procctl(Proc *p)
{
	char *state;
	ulong s;

	switch(p->procctl) {
	case Proc_exitbig:
		spllo();
		pexit("Killed: Insufficient physical memory", 1);

	case Proc_exitme:
		spllo();		/* pexit has locks in it */
		pexit("Killed", 1);

	case Proc_traceme:
		if(p->nnote == 0)
			return;
		/* No break */

	case Proc_stopme:
		p->procctl = 0;
		state = p->psstate;
		p->psstate = "Stopped";
		/* free a waiting debugger */
		s = spllo();
		qlock(&p->debug);
		if(p->pdbg) {
			wakeup(&p->pdbg->sleep);
			p->pdbg = 0;
		}
		qunlock(&p->debug);
		splhi();
		p->state = Stopped;
		if (edf->isedf(up))
			edf->edfblock(up);
		sched();
		p->psstate = state;
		splx(s);
		return;
	}
}

#include "errstr.h"

void
error(char *err)
{
	spllo();
	kstrcpy(up->errstr, err, ERRMAX);
	setlabel(&up->errlab[NERR-1]);
	nexterror();
}

void
nexterror(void)
{
	gotolabel(&up->errlab[--up->nerrlab]);
}

void
exhausted(char *resource)
{
	char buf[ERRMAX];

	sprint(buf, "no free %s", resource);
	iprint("%s\n", buf);
	error(buf);
}

void
killbig(void)
{
	int i;
	Segment *s;
	ulong l, max;
	Proc *p, *ep, *kp;

	max = 0;
	kp = 0;
	ep = procalloc.arena+conf.nproc;
	for(p = procalloc.arena; p < ep; p++) {
		if(p->state == Dead || p->kp)
			continue;
		l = 0;
		for(i=1; i<NSEG; i++) {
			s = p->seg[i];
			if(s != 0)
				l += s->top - s->base;
		}
		if(l > max && strcmp(p->text, "kfs") != 0){
			kp = p;
			max = l;
		}
	}
	kp->procctl = Proc_exitbig;
	for(i = 0; i < NSEG; i++) {
		s = kp->seg[i];
		if(s != 0 && canqlock(&s->lk)) {
			mfreeseg(s, s->base, (s->top - s->base)/BY2PG);
			qunlock(&s->lk);
		}
	}
	print("%lud: %s killed because no swap configured\n", kp->pid, kp->text);
}

/*
 *  change ownership to 'new' of all processes owned by 'old'.  Used when
 *  eve changes.
 */
void
renameuser(char *old, char *new)
{
	Proc *p, *ep;

	ep = procalloc.arena+conf.nproc;
	for(p = procalloc.arena; p < ep; p++)
		if(p->user!=nil && strcmp(old, p->user)==0)
			kstrdup(&p->user, new);
}

/*
 *  time accounting called by clock() splhi'd
 */
void
accounttime(void)
{
	Proc *p;
	ulong n, per;
	static ulong nrun;

	p = m->proc;
	if(p) {
		nrun++;
		p->time[p->insyscall]++;
	}

	/* calculate decaying duty cycles */
	n = perfticks();
	per = n - m->perf.last;
	m->perf.last = n;
	per = (m->perf.period*(HZ-1) + per)/HZ;
	if(per != 0)
		m->perf.period = per;

	m->perf.avg_inidle = (m->perf.avg_inidle*(HZ-1)+m->perf.inidle)/HZ;
	m->perf.inidle = 0;

	m->perf.avg_inintr = (m->perf.avg_inintr*(HZ-1)+m->perf.inintr)/HZ;
	m->perf.inintr = 0;

	/* only one processor gets to compute system load averages */
	if(m->machno != 0)
		return;

	/* calculate decaying load average */
	n = nrun;
	nrun = 0;
	n = (nrdy+n)*1000;
	m->load = (m->load*19+n)/20;
}

static void
pidhash(Proc *p)
{
	int h;

	h = p->pid % nelem(procalloc.ht);
	lock(&procalloc);
	p->pidhash = procalloc.ht[h];
	procalloc.ht[h] = p;
	unlock(&procalloc);
}

static void
pidunhash(Proc *p)
{
	int h;
	Proc **l;

	h = p->pid % nelem(procalloc.ht);
	lock(&procalloc);
	for(l = &procalloc.ht[h]; *l != nil; l = &(*l)->pidhash)
		if(*l == p){
			*l = p->pidhash;
			break;
		}
	unlock(&procalloc);
}

int
procindex(ulong pid)
{
	Proc *p;
	int h;
	int s;

	s = -1;
	h = pid % nelem(procalloc.ht);
	lock(&procalloc);
	for(p = procalloc.ht[h]; p != nil; p = p->pidhash)
		if(p->pid == pid){
			s = p - procalloc.arena;
			break;
		}
	unlock(&procalloc);
	return s;
}