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Subject: Re: [ANNOUNCE] Ext3 vs Reiserfs benchmarks
From: Chris Mason <mason@suse.com>
To: Dax Kelson <dax@gurulabs.com>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <1026490866.5316.41.camel@thud>
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Date: 12 Jul 2002 16:34:53 -0400
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On Fri, 2002-07-12 at 12:21, Dax Kelson wrote:
> Tested:
> 
> ext3 data=ordered
> ext3 data=writeback
> reiserfs
> reiserfs notail
> 
> http://www.gurulabs.com/ext3-reiserfs.html
> 
> Any suggestions or comments appreciated.

postmark is an interesting workload, but it does not do fsync or renames
on the working set, and postfix does lots of both while delivering. 
postmark does do a good job of showing the difference between lots of
files in one directory (great for reiserfs) and lots of directories with
fewer files in each (better for ext3).

Andreas Dilger already mentioned -o data=journal on ext3, you can try
the beta reiserfs patches that add support for data=journal and
data=ordered at:

ftp.suse.com/pub/people/mason/patches/data-logging

They improve reiserfs performance for just about everything, but
data=journal is especially good for fsync/O_SYNC heavy workloads.

Andrew Morton sent me a benchmark of his that tries to simulate
postfix.  He has posted it to l-k before but a quick google search found
dead links only, so I'm attaching it.  What I like about his synctest is
the results are consistent and you can play with various
fsync/rename/unlink options.

-chris


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/*
 * Test and benchmark synchronous operations.
 * stolen from Andrew Morton
 */

#undef _XOPEN_SOURCE	/* MAP_ANONYMOUS */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <sys/mman.h>

/*
 * Lots of yummy globals!
 */
char *progname, *dirname;
int verbose, use_fsync, use_osync;
int fsync_dir;
int n_threads =3D 1, n_iters =3D 100;
int *child_status;
int this_child_index;
int dir_fd;
int show_tids;
int threads_per_dir =3D 1;
int thread_group;
int do_unlink;
int rename_pass;

#define N_FILES		100
#define UNLINK_LAG	30
#define RENAME_PASSES	3

void show(char *fmt, ...)
{
	if (verbose) {
		va_list ap;

		va_start(ap, fmt);
		vfprintf(stdout, fmt, ap);
		fflush( stdout );
		va_end(ap);
	}
}

/*
 * - Create a file.
 * - Write some data to it
 * - Maybe fsync() it.
 * - Close it
 * - Maybe fsync() its parent dir
 * - rename() it.
 * - maybe fsync() its parent dir
 * - rename() it.
 * - maybe fsync() its parent dir
 * - rename() it.
 * - maybe fsync() its parent dir
 * - UNLINK_LAG files later, maybe unlink it.
 * - maybe fsync() its parent dir
 *
 * Repeat the above N_FILES times
 */

char *mk_dirname(void)
{
	char *ret =3D malloc(strlen(dirname) + 64);

	sprintf(ret, "%s/%05d", dirname, thread_group);
	return ret;
}

char *mk_filename(int fileno)
{
	char *ret =3D malloc(strlen(dirname) + 64);

	sprintf(ret, "%s/%05d/%05d-%05d",
			dirname, thread_group, getpid(), fileno);
	return ret;
}

char *mk_new_filename(int fileno, int pass)
{
	char *ret =3D malloc(strlen(dirname) + 64);

	sprintf(ret, "%s/%05d/%02d-%05d-%05d",
			dirname, thread_group, pass, getpid(), fileno);
	return ret;
}

void sync_dir(void)
{
	if (fsync_dir) {
		show("fsync(%s)\n", dirname);
		if (fsync(dir_fd) < 0) {
			fprintf(stderr, "%s: failed to fsync dir `%s': %s\n",
				progname, dirname, strerror(errno));
			exit(1);
		}
	}
}

void make_dir(void)
{
	char *n =3D mk_dirname();

	show("mkdir(%s)\n", n);
	if (mkdir(n, 0777) < 0) {
		fprintf(stderr, "%s: Cannot make directory `%s': %s\n",
			progname, n, strerror(errno));
		exit(1);
	}
	free(n);
}

void remove_dir(void)
{
	char *n =3D mk_dirname();
	show("rmdir(%s)\n", n);
	rmdir(n);
	free(n);
}

void write_stuff_to(int fd, char *name)
{
	static char buf[500000];
	static int to_write =3D 5000;

	show("write %d bytes to `%s'\n", sizeof(buf), name);
	if (write(fd, buf, to_write) !=3D to_write) {
		fprintf(stderr, "%s: failed to write %d bytes to `%s': %s\n",
			progname, to_write, name, strerror(errno));
		exit(1);
	}

	to_write *=3D 1.1;
	if (to_write > 250000)
		to_write =3D 5000;
}

void unlink_one_file(int fileno, int pass)
{
	if (do_unlink) {
		char *name =3D mk_new_filename(fileno, pass);

		show("unlink(%s)\n", name);
		if (unlink(name) < 0) {
			fprintf(stderr, "%s: failed to unlink `%s': %s\n",
				progname, name, strerror(errno));
			exit(1);
		}
		sync_dir();
		free(name);
	}
}

void do_one_file(int fileno)
{
	char *name =3D mk_filename(fileno);
	int fd, flags;

	flags =3D O_RDWR|O_CREAT|O_TRUNC;
	if (use_osync)
		flags |=3D O_SYNC;

	show("open(%s)\n", name);
	fd =3D open(name, flags, 0666);
	if (fd < 0) {
		fprintf(stderr, "%s: failed to create file `%s': %s\n",
			progname, name, strerror(errno));
		exit(1);
	}

	write_stuff_to(fd, name);

	if (use_fsync) {
		show("fsync(%s)\n", name);
		if (fsync(fd) < 0) {
			fprintf(stderr, "%s: failed to fsync `%s': %s\n",
				progname, name, strerror(errno));
			exit(1);
		}
	}

	show("close(%s)\n", name);
	if (close(fd) < 0) {
		fprintf(stderr, "%s: failed to close `%s': %s\n",
			progname, name, strerror(errno));
		exit(1);
	}

	sync_dir();

	for (rename_pass =3D 0; rename_pass < RENAME_PASSES; rename_pass++) {
		char *newname =3D mk_new_filename(fileno, rename_pass);

		show("rename(%s, %s)\n", name, newname);
		if (rename(name, newname) < 0) {
			fprintf(stderr,
				"%s: failed to rename `%s' to `%s': %s\n",
				progname, name, newname, strerror(errno));
			exit(1);
		}
		sync_dir();
		free(name);
		name =3D newname;
	}
	rename_pass--;
	free(name);
}

void do_child(void)
{
	int fileno;
	char *dn =3D mk_dirname();
	int dotcount;

	dir_fd =3D open(dn, O_RDONLY);
	if (dir_fd < 0) {
		fprintf(stderr, "%s: failed to open dir `%s': %s\n",
			progname, dn, strerror(errno));
		exit(1);
	}
	free(dn);

	dotcount =3D N_FILES / 10;
	if (dotcount =3D=3D 0)
		dotcount =3D 1;

	for (fileno =3D 0; fileno < N_FILES; fileno++) {
		if (fileno % dotcount =3D=3D 0) {
			printf(".");
			fflush(stdout);
		}
		do_one_file(fileno);
		if (fileno >=3D UNLINK_LAG)
			unlink_one_file(fileno - UNLINK_LAG, RENAME_PASSES - 1);
	}
	for (fileno =3D N_FILES - UNLINK_LAG; fileno < N_FILES; fileno++)
		unlink_one_file(fileno, RENAME_PASSES - 1);
}

void doit(void)
{
	int child;
	int children_left;

	child_status =3D (int *)mmap(	0,
				n_threads * sizeof(*child_status),
				PROT_READ|PROT_WRITE,
				MAP_SHARED|MAP_ANONYMOUS,
				-1,
				0);
	if (child_status =3D=3D MAP_FAILED) {
		perror("mmap");
		exit(1);
	}

	memset(child_status, 0, n_threads * sizeof(*child_status));

	thread_group =3D -1;
	for (this_child_index =3D 0;
			this_child_index < n_threads; this_child_index++)
	{
		if (this_child_index % threads_per_dir =3D=3D 0) {
			thread_group++;
			make_dir();
		}

		if (fork() =3D=3D 0) {
			int iter;

			for (iter =3D 0; iter < n_iters; iter++)
				do_child();
			child_status[this_child_index] =3D 1;
			exit(0);
		}
	}

	/* Parent */
	children_left =3D n_threads;
	while (children_left) {
		int status;

		if( wait3(&status, 0, 0) < 0 ) {
			if( errno !=3D EINTR ) {
				perror("wait3");
				exit(1);
			}
			continue;
		}
		for (child =3D 0; child < n_threads; child++) {
			if (child_status[child] =3D=3D 1) {
				child_status[child] =3D 2;
				printf("*");
				fflush(stdout);
				children_left--;
			}
		}
	}
	for (thread_group =3D 0;=20
			thread_group < ( n_threads / threads_per_dir );=20
			thread_group++ )
		remove_dir();

	printf("\n");
}

void usage(void)
{
	fprintf(stderr,
		"Usage: %s [-fFosuv] [-p threads-pre-dir ][-n iters] [-t threads] dirname=
\n",
			progname);
	fprintf(stderr, "        -f:    Use fsync() on close\n");=20
	fprintf(stderr, "        -F:    Use fsync() on parent dir\n");=20
	fprintf(stderr, "        -n:    Number of iterations\n");
	fprintf(stderr, "        -o:    Open files O_SYNC\n");
	fprintf(stderr, "        -p:    Number of threads per directory\n");
	fprintf(stderr, "        -t:    Number of threads\n");
	fprintf(stderr, "        -u:    Unlink files during test\n");
	fprintf(stderr, "        -v:    Verbose\n");=20
	fprintf(stderr, "   dirname:    Directory to run tests in\n");
	exit(1);
}


int main(int argc, char *argv[])
{
	int c;

	progname =3D argv[0];
	while ((c =3D getopt(argc, argv, "vFfout:n:p:")) !=3D -1) {
		switch (c) {
		case 'f':
			use_fsync++;
			break;
		case 'F':
			fsync_dir++;
			break;
		case 'n':
			n_iters =3D strtol(optarg, NULL, 10);
			break;
		case 'o':
			use_osync++;
			break;
		case 'p':
			threads_per_dir =3D strtol(optarg, NULL, 10);
			break;
		case 't':
			n_threads =3D strtol(optarg, NULL, 10);
			break;
		case 'u':
			do_unlink++;
			break;
		case 'v':
			verbose++;
			break;
		}
	}

	if (optind =3D=3D argc)
		usage();
	dirname =3D argv[optind++];
	if (optind !=3D argc)
		usage();

	doit();
	exit(0);
}

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