[9fans] io patterns

[erik quanstrom <quanstro@quanstro.net>]

[-- Attachment #1: Type: text/plain, Size: 791 bytes --]

to beat a dead horse to death, i spent a few minutes writing a little
test program inspired by the little programming language in igbe for
bit-banging the atmel part.  a minimal primer
o	set offset (in bytes)
{}	set up timing
: n ;	loop
r/w	read/write
s	seek {n sectors, or 'r' random}
z	set sector size

so this little program times 1000 sectors of sequential read io
	{:1000 rs1 ;}
and this one skips sectors

so this little program times 1000 sectors of sequential read io
	{:1000 rs1 ;}
and this one would read every other sector
	{:1000 rs2 ;}

new# iop -p '{:1000 rs2 ;}' data
0.061
16220.14 iops
new# iop -p '{:1000 rs2 ;}' data
0.299
3340.96 iops

i think the 4k sector test would then be

	for(i in 1 2 3 4) iop -p z4096o$i^'{:1000 rs1 ;}' data

- erik

[-- Attachment #2: iop.c --]
[-- Type: text/plain, Size: 2749 bytes --]

#include <u.h>
#include <libc.h>

enum {
	Nanoi	= 1000000000,	/* 1/nano */
	Microi	= 1000000,
};

void
ioloop(int fd, uvlong bytes, char *prog)
{
	char *buf, *p, *loop;
	int l;
	uint ss, iops;
	uvlong byte0, maxlba, lba, t, x;

	/* silence compiler */
	iops = 0;
	l = 0;
	t = 0;

	loop = nil;
	byte0 = 0;
	lba = 0;
	ss = 512;
	maxlba = (bytes - byte0) / ss;
	buf = malloc(ss);
	if(buf == nil)
		sysfatal("malloc");
	srand(nsec());
	for(p = prog;; ){
		switch(*p){
		default:
			sysfatal("bad char %c in prog %s\n", *p, prog);
		case 0:
			goto end;
		case ' ':
			break;
		case ':':							/* loop */
			l = strtol(p+1, &loop, 0);
			p = loop;
			continue;
		case ';':							/* end */
			if(loop == nil)
				sysfatal("malformd loop: extra ';'");
			if(--l > 0){
				p = loop;
				continue;
			}
			loop = nil;
			break;
		case '{':
			iops = 0;
			t = - nsec();
			break;
		case '}':
			t += nsec();
			print("%lld.%03lld\n", t/Nanoi, (t%Nanoi)/Microi);
			x = (uvlong)iops*(uvlong)Nanoi*100;
			x /= t;
			print("%lld.%02lld iops\n", x/100, (x%100));
			break;
		case 'o':
			byte0 = strtoull(p, &p, 0);
			maxlba = (bytes - byte0) / ss;
			continue;
		case 'z':
			ss = strtoul(p, &p, 0);
			if(ss == 0)
				sysfatal("sector size zero");
			maxlba = (bytes - byte0) / ss;
			buf = realloc(buf, ss);
			if(buf == nil)
				sysfatal("realloc: %r");
			break;
		case 'r':							/* read */
			pread(fd, buf, ss, byte0 + lba*ss);
			iops++;
			break;
		case 'w':							/* write */
			pwrite(fd, buf, ss, byte0 + lba*ss);
			iops++;
			break;
		case 's':							/* seek */
			switch(p[1]){
			default:
				sysfatal("seek requires argument\n");
			case 'r':
				lba = frand()*maxlba;	/* awful.  no vlnrand() */
				p++;
				break;
			case 's':
				p++;
			case '0': case '1': case '2': case '3': case '4':
			case '5': case '6': case '7': case '8': case '9':
				p++;
				lba += strtol(p, &p, 0);
				break;
			}
			continue;
		}
		p++;
	}
end:
	free(buf);
}

void
usage(void)
{
	fprint(2, "usage: iop [-p prog] ... [file ...]\n");
	exits("usage");
}

void
main(int argc, char **argv)
{
	char *prog[25];
	int i, j, nprog, fd;
	uvlong bytes;
	Dir *d;

	nprog = 0;

	ARGBEGIN{
	case 'p':
		if(nprog == nelem(prog))
			sysfatal("too many programs");
		prog[nprog++] = EARGF(usage());
		break;
	default:
		usage();
	}ARGEND;

	for(i = 0; i < argc; i++){
		d = dirstat(argv[i]);
		if(d == nil)
			sysfatal("dirstat: %r");
		bytes = d->length;
		free(d);

		fd = open(argv[i], ORDWR);
		if(fd == -1)
			sysfatal("open: %r");
		for(j = 0; j < nprog; j++)
			ioloop(fd, bytes, prog[i]);
		close(fd);
	}
	exits("");
}