add image statistics to /dev/debug
make /dev/debug big enough to do useful stuff

Reference: /n/atom/patch/applied/imagestats
Date: Thu Jun 12 04:37:41 CES 2014
Signed-off-by: quanstro@quanstro.net

--- /sys/src/nix/port/portfns.h	Thu Jun 12 04:37:08 2014
+++ /sys/src/nix/port/portfns.h	Thu Jun 12 04:37:10 2014
@@ -126,6 +126,7 @@
 Block*		iallocb(int);
 void		iallocsummary(void);
 void		ilock(Lock*);
+char*		imagestats(char*, char*);
 int		incref(Ref*);
 void		initimage(void);
 void		interruptsummary(void);
--- /sys/src/nix/port/image.c	Thu Jun 12 04:37:12 2014
+++ /sys/src/nix/port/image.c	Thu Jun 12 04:37:14 2014
@@ -18,11 +18,24 @@
 } imagealloc;
 
 static struct {
-	int	calls;			/* times imagereclaim was called */
+	int	attachimage;		/* number of attach images */
+	int	found;			/* number of images found */
+	int	reclaims;			/* times imagereclaim was called */
 	uvlong	ticks;			/* total time in the main loop */
 	uvlong	maxt;			/* longest time in main loop */
 } irstats;
 
+char*
+imagestats(char *p, char *e)
+{
+	p = seprint(p, e, "image reclaims: %d\n", irstats.reclaims);
+	p = seprint(p, e, "image µs: %lld\n", fastticks2us(irstats.ticks));
+	p = seprint(p, e, "image max µs: %lld\n", fastticks2us(irstats.maxt));
+	p = seprint(p, e, "image attachimage: %d\n", irstats.attachimage);
+	p = seprint(p, e, "image found: %d\n", irstats.found);
+	return p;
+}
+
 /*
  * imagealloc and i must be locked.
  */
@@ -104,10 +117,9 @@
 	uint sz;
 	uvlong ticks0, ticks;
 
-	irstats.calls++;
-	/* Somebody is already cleaning the page cache */
 	if(!canqlock(&imagealloc.ireclaim))
 		return 0;
+	irstats.reclaims++;
 	ticks0 = fastticks(nil);
 
 	sz = pagereclaim();
@@ -127,6 +139,7 @@
 	Image *i, **l;
 
 	lock(&imagealloc);
+	irstats.attachimage++;
 
 	/*
 	 * Search the image cache for remains of the text from a previous
@@ -139,6 +152,7 @@
 			   eqqid(c->mqid, i->mqid) &&
 			   c->mchan == i->mchan &&
 			   c->dev->dc == i->dc) {
+				irstats.found++;
 				goto found;
 			}
 			unlock(i);
--- /sys/src/nix/port/devcons.c	Thu Jun 12 04:37:18 2014
+++ /sys/src/nix/port/devcons.c	Thu Jun 12 04:37:19 2014
@@ -822,8 +822,8 @@
 {
 	ulong l;
 	Mach *mp;
-	char *b, *bp, ch, *s, *e, tmp[512];
-	int i, k, id, send;
+	char *b, *bp, ch, *s, *p, *e, tmp[512];
+	int i, k, id, send, r;
 	long offset;
 	extern int schedsteals;
 
@@ -1031,16 +1031,27 @@
 		return n;
 
 	case Qdebug:
-		e = tmp + sizeof tmp;
-		s = seprint(tmp, e, "steal %d\n", schedsteals);
-		s = seprint(s, e, "locks %llud\n", lockstats.locks);
-		s = seprint(s, e, "glare %llud\n", lockstats.glare);
-		s = seprint(s, e, "inglare %llud\n", lockstats.inglare);
-		s = seprint(s, e, "qlock %llud\n", qlockstats.qlock);
-		s = seprint(s, e, "qlockq %llud\n", qlockstats.qlockq);
-		qiostats(s, e);
-		return readstr(offset, buf, n, tmp);
-		break;
+		s = malloc(READSTR);
+		if(s == nil)
+			error(Enomem);
+		if(waserror()){
+			free(s);
+			nexterror();
+		}
+		p = s;	
+		e = s +READSTR;
+		p = seprint(p, e, "steal %d\n", schedsteals);
+		p = seprint(p, e, "locks %llud\n", lockstats.locks);
+		p = seprint(p, e, "glare %llud\n", lockstats.glare);
+		p = seprint(p, e, "inglare %llud\n", lockstats.inglare);
+		p = seprint(p, e, "qlock %llud\n", qlockstats.qlock);
+		p = seprint(p, e, "qlockq %llud\n", qlockstats.qlockq);
+		p = imagestats(p, e);
+		qiostats(p, e);
+		r = readstr(offset, buf, n, s);
+		poperror();
+		free(s);
+		return r;
 	default:
 		print("consread %#llux\n", c->qid.path);
 		error(Egreg);