diff --git a/sys/src/cmd/aux/mkfile b/sys/src/cmd/aux/mkfile
index 943ae06f2..3cc2a3dd0 100644
--- a/sys/src/cmd/aux/mkfile
+++ b/sys/src/cmd/aux/mkfile
@@ -31,6 +31,7 @@ TARG=\
 	rdwr\
 	reboot\
 	searchfs\
+	seek\
 	statusbar\
 	stub\
 	tablet\
diff --git a/sys/src/cmd/aux/seek.c b/sys/src/cmd/aux/seek.c
new file mode 100644
index 000000000..134463b91
--- /dev/null
+++ b/sys/src/cmd/aux/seek.c
@@ -0,0 +1,33 @@
+#include <u.h>
+#include <libc.h>
+
+void
+main(int argc, char **argv)
+{
+	char buf[512];
+	vlong size;
+	vlong pos;
+	vlong ns;
+	int fd;
+	int i;
+
+	if(argc != 2) {
+		fprint(2, "usage: %s /dev/sd??/data\n", argv[0]);
+		exits("usage");
+	}
+	
+	srand(time(0));
+	fd = open(argv[1], OREAD);
+	if(fd < 0)
+		sysfatal("open: %r");
+	size = seek(fd, 0, 2) / 512;
+	ns = nsec();
+	for(i=0;i<100;i++) {
+		pos = (vlong)(frand() * size);
+		if(pread(fd, buf, 512, 512 * pos) < 512)
+			sysfatal("read: %r");
+	}
+	ns = nsec() - ns;
+	print("%.3g\n", ((double)ns)/100000000);
+	exits(nil);
+}