fossil: import from plan 9

R=rsc
https://codereview.appspot.com/7988047

src/cmd/fossil/9ping.c

@@ -0,0 +1,109 @@
+#include <u.h>
+#include <libc.h>
+
+typedef uvlong u64int;
+
+#define TWID64	((u64int)~(u64int)0)
+
+
+u64int
+unittoull(char *s)
+{
+	char *es;
+	u64int n;
+
+	if(s == nil)
+		return TWID64;
+	n = strtoul(s, &es, 0);
+	if(*es == 'k' || *es == 'K'){
+		n *= 1024;
+		es++;
+	}else if(*es == 'm' || *es == 'M'){
+		n *= 1024*1024;
+		es++;
+	}else if(*es == 'g' || *es == 'G'){
+		n *= 1024*1024*1024;
+		es++;
+	}
+	if(*es != '\0')
+		return TWID64;
+	return n;
+}
+
+void
+main(int argc, char *argv[])
+{
+	int fd, i;
+	int n = 1000, m;
+	int s = 1;
+	double *t, t0, t1;
+	uchar *buf;	
+	double a, d, max, min;
+
+	m = OREAD;
+	ARGBEGIN{
+	case 'n':
+		n = atoi(ARGF());
+		break;
+	case 's':
+		s = unittoull(ARGF());
+		if(s < 1 || s > 1024*1024)
+			sysfatal("bad size");
+		break;
+	case 'r':
+		m = OREAD;
+		break;
+	case 'w':
+		m = OWRITE;
+		break;
+	}ARGEND
+
+	fd = 0;
+	if(argc == 1){
+		fd = open(argv[0], m);
+		if(fd < 0)
+			sysfatal("could not open file: %s: %r", argv[0]);
+	}
+
+	buf = malloc(s);
+	t = malloc(n*sizeof(double));
+	
+	t0 = nsec();
+	for(i=0; i<n; i++){
+		if(m == OREAD){
+			if(pread(fd, buf, s, 0) < s)
+				sysfatal("bad read: %r");
+		}else{
+			if(pwrite(fd, buf, s, 0) < s)
+				sysfatal("bad write: %r");
+		}
+		t1 = nsec();
+		t[i] = (t1 - t0)*1e-3;
+		t0 = t1;
+	}
+
+	a = 0.;
+	d = 0.;
+	max = 0.;
+	min = 1e12;
+
+	for(i=0; i<n; i++){
+		a += t[i];
+		if(max < t[i])
+			max = t[i];
+		if(min > t[i])
+			min = t[i];
+	}
+
+	a /= n;
+	
+	for(i=0; i<n; i++)
+		d += (a - t[i]) * (a - t[i]);
+	d /= n;
+	d = sqrt(d);
+
+	print("avg = %.0fµs min = %.0fµs max = %.0fµs dev = %.0fµs\n", a, min, max, d);
+
+	exits(0);
+}
+