7 files changed, 64 insertions(+), 69 deletions(-)

M port/devcons.c
M port/fault.c
M port/portdat.h
M port/portfns.h
M port/proc.c
M port/qlock.c
M port/swap.c

@@ 233,6 233,7 @@ echo(Rune r, char *buf, int n)
 			xsummary();
 			ixsummary();
 			poolsummary();
+			pagersummary();
 			break;
 		case 'd':
 			if(consdebug != nil)

@@ 95,13 95,9 @@ fixfault(Segment *s, ulong addr, int read, int doputmmu)
 		lkp = *pg;
 		lock(lkp);
 
-		/* uncache the current swap image (since we may be changing it) */
-		if(lkp->image){
-			if(lkp->image == &swapimage)
-				uncachepage(lkp);
-			else
-				duppage(lkp);
-		}
+		/* save a copy of the original for the image cache */
+		if(lkp->image)
+			duppage(lkp);
 
 		unlock(lkp);
 		goto done;


@@ 153,16 149,9 @@ fixfault(Segment *s, ulong addr, int read, int doputmmu)
 			putpage(lkp);
 		}
 		else {
-			/* uncache the current page (since we may be changing it)
-			 * and, if a text page, put a duplicate back onto
-			 * the free list
-			 */
-			if(lkp->image){
-				if(lkp->image == &swapimage)
-					uncachepage(lkp);
-				else
-					duppage(lkp);
-			}
+			/* save a copy of the original for the image cache */
+			if(lkp->image)
+				duppage(lkp);
 
 			unlock(lkp);
 		}


@@ 200,7 189,7 @@ fixfault(Segment *s, ulong addr, int read, int doputmmu)
 void
 pio(Segment *s, ulong addr, ulong soff, Page **p)
 {
-	Page *new, *new2;
+	Page *new;
 	KMap *k;
 	Chan *c;
 	int n, ask;


@@ 208,22 197,26 @@ pio(Segment *s, ulong addr, ulong soff, Page **p)
 	ulong daddr;
 	Page *loadrec;
 
+retry:
 	loadrec = *p;
 	if(loadrec == 0) {	/* from a text/data image */
 		daddr = s->fstart+soff;
 		new = lookpage(s->image, daddr);
+		if(new != nil) {
+			*p = new;
+			return;
+		}
 	}
 	else {			/* from a swap image */
 		daddr = swapaddr(loadrec);
 		new = lookpage(&swapimage, daddr);
-		if(new != nil)
+		if(new != nil) {
 			putswap(loadrec);
+			*p = new;
+			return;
+		}
 	}
 
-	if(new != nil) {			/* Page found from cache */
-		*p = new;
-		return;
-	}
 
 	qunlock(&s->lk);
 


@@ 254,7 247,11 @@ pio(Segment *s, ulong addr, ulong soff, Page **p)
 		poperror();
 		kunmap(k);
 		qlock(&s->lk);
-		/* race, we may have multiple simultaneous reads */
+
+		/*
+		 *  race, another proc may have gotten here first while
+		 *  s->lk was unlocked
+		 */
 		if(*p == 0) { 
 			new->daddr = daddr;
 			cachepage(new, s->image);


@@ 265,35 262,9 @@ pio(Segment *s, ulong addr, ulong soff, Page **p)
 	}
 	else {				/* This is paged out */
 		c = swapimage.c;
-		qlock(&swapimage.rdlock);	/* mutex */
-
-		/*
-		 *  multiple processes could be swapping in the
-		 *  same page for the same segment
-		 */
-		if(!pagedout(*p)){
-			putpage(new);
-			qunlock(&swapimage.rdlock);
-			goto done;
-		}
-
-		/*
-		 *  multiple processes could be swapping in the
-		 *  same page for different segments
-		 */
-		new2 = lookpage(&swapimage, daddr);
-		if(new2 != nil){
-			putpage(new);
-			*p = new2;
-			putswap(loadrec);
-			qunlock(&swapimage.rdlock);
-			goto done;
-		}
-
 		if(waserror()) {
 			kunmap(k);
 			putpage(new);
-			qunlock(&swapimage.rdlock);
 			qlock(&s->lk);
 			qunlock(&s->lk);
 			faulterror("sys: page in I/O error");


@@ 307,12 278,28 @@ pio(Segment *s, ulong addr, ulong soff, Page **p)
 		kunmap(k);
 		qlock(&s->lk);
 
+		/*
+		 *  race, another proc may have gotten here first
+		 *  (and the pager may have run on that page) while
+		 *  s->lk was unlocked
+		 */
+		if(*p != loadrec){
+			if(!pagedout(*p)){
+				/* another process did it for me */
+				putpage(new);
+				goto done;
+			} else {
+print("!");
+				/* another process and the pager got in */
+				putpage(new);
+				goto retry;
+			}
+		}
+
 		new->daddr = daddr;
 		cachepage(new, &swapimage);
 		*p = new;
 		putswap(loadrec);
-
-		qunlock(&swapimage.rdlock);
 	}
 
 done:

@@ 326,7 326,6 @@ struct Image
 	Image	*hash;			/* Qid hash chains */
 	Image	*next;			/* Free list */
 	int	notext;			/* no file associated */
-	QLock	rdlock;			/* mutex for reading from image */
 };
 
 struct Pte


@@ 622,6 621,7 @@ struct Proc
 	int	preempted;	/* true if this process hasn't finished the interrupt
 				 *  that last preempted it
 				 */
+	ulong	qpc;		/* pc calling last blocking qlock */
 
 	void	*ureg;		/* User registers for notes */
 	void	*dbgreg;	/* User registers for devproc */

@@ 174,6 174,7 @@ Block*		packblock(Block*);
 Block*		padblock(Block*, int);
 void		pagechainhead(Page*);
 void		pageinit(void);
+void		pagersummary(void);
 void		panic(char*, ...);
 int		parseether(uchar*, char*);
 int		parsefields(char*, char**, int, char*);

@@ 903,9 903,9 @@ dumpaproc(Proc *p)
 	s = p->psstate;
 	if(s == 0)
 		s = "kproc";
-	print("%3lud:%10s pc %8lux dbgpc %8lux  %8s (%s) ut %ld st %ld bss %lux pri %lud\n",
+	print("%3lud:%10s pc %8lux dbgpc %8lux  %8s (%s) ut %ld st %ld bss %lux qpc %lux\n",
 		p->pid, p->text, p->pc, dbgpc(p),  s, statename[p->state],
-		p->time[0], p->time[1], bss, p->priority);
+		p->time[0], p->time[1], bss, p->qpc);
 }
 
 void

@@ 35,6 35,7 @@ rwstats.qlockq++;
 	q->tail = mp;
 	mp->qnext = 0;
 	mp->state = Queueing;
+	up->qpc = getcallerpc(q);
 	unlock(&q->use);
 	sched();
 }

@@ 124,7 124,9 @@ loop:
 			if(p->state == Dead || p->kp)
 				continue;
 
-			qlock(&p->seglock);
+			if(!canqlock(&p->seglock))
+				continue;		/* process changing its segments */
+
 			for(i = 0; i < NSEG; i++) {
 				if(!needpages(junk)){
 					qunlock(&p->seglock);


@@ 278,19 280,6 @@ pagepte(int type, Page **pg)
 	case SG_SHARED:
 	case SG_SHDATA:
 	case SG_MAP:
-		/* if it's already on disk, no need to do io again */
-#ifdef asdf
-		lock(outp);
-		if(outp->image == &swapimage){
-			dupswap((Page*)outp->daddr);
-			*pg = (Page*)(outp->daddr|PG_ONSWAP);
-			unlock(outp);
-			putpage(outp);
-			return;
-		}
-		unlock(outp);
-#endif asdf
-
 		/*
 		 *  get a new swap address and clear any pages
 		 *  referring to it from the cache


@@ 312,6 301,7 @@ pagepte(int type, Page **pg)
 		/*
 		 *  enter it into the cache so that a fault happening
 		 *  during the write will grab the page from the cache
+		 *  rather than one partially written to the disk
 		 */
 		outp->daddr = daddr;
 		cachepage(outp, &swapimage);


@@ 324,6 314,15 @@ pagepte(int type, Page **pg)
 	}
 }
 
+void
+pagersummary(void)
+{
+	print("%lud/%lud memory %lud/%lud swap %d iolist\n",
+		palloc.user-palloc.freecount,
+		palloc.user, conf.nswap-swapalloc.free, conf.nswap,
+		ioptr);
+}
+
 static void
 executeio(void)
 {


@@ 336,13 335,17 @@ executeio(void)
 	c = swapimage.c;
 
 	for(i = 0; i < ioptr; i++) {
+		if(ioptr > conf.nswppo)
+			panic("executeio: ioptr %d > %d\n", ioptr, conf.nswppo);
 		out = iolist[i];
+		up->psstate = "I/Okm";
 		k = kmap(out);
 		kaddr = (char*)VA(k);
 
 		if(waserror())
 			panic("executeio: page out I/O error");
 
+		up->psstate = "I/Owr";
 		n = devtab[c->type]->write(c, kaddr, BY2PG, out->daddr);
 		if(n != BY2PG)
 			nexterror();


@@ 351,9 354,11 @@ executeio(void)
 		poperror();
 
 		/* Free up the page after I/O */
+		up->psstate = "I/Odec";
 		lock(out);
 		out->ref--;
 		unlock(out);
+		up->psstate = "I/Oput";
 		putpage(out);
 	}
 	ioptr = 0;