[fio.git] / log.c

/*
 * Code related to writing an iolog of what a thread is doing, and to
 * later read that back and replay
 */
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "list.h"
#include "fio.h"

static const char iolog_ver2[] = "fio version 2 iolog";

void queue_io_piece(struct thread_data *td, struct io_piece *ipo)
{
	list_add_tail(&ipo->list, &td->io_log_list);
	td->total_io_size += ipo->len;
}

void log_io_u(struct thread_data *td, struct io_u *io_u)
{
	const char *act[] = { "read", "write", "sync" };

	assert(io_u->ddir < 3);

	if (!td->o.write_iolog_file)
		return;

	fprintf(td->iolog_f, "%s %s %llu %lu\n", io_u->file->file_name,
						act[io_u->ddir], io_u->offset,
						io_u->buflen);
}

void log_file(struct thread_data *td, struct fio_file *f,
	      enum file_log_act what)
{
	const char *act[] = { "add", "open", "close" };

	assert(what < 3);

	if (!td->o.write_iolog_file)
		return;

	fprintf(td->iolog_f, "%s %s\n", f->file_name, act[what]);
}

static void iolog_delay(struct thread_data *td, unsigned long delay)
{
	unsigned long usec = utime_since_now(&td->last_issue);

	if (delay < usec)
		return;

	delay -= usec;

	/*
	 * less than 100 usec delay, just regard it as noise
	 */
	if (delay < 100)
		return;

	usec_sleep(td, delay);
}

static int ipo_special(struct thread_data *td, struct io_piece *ipo)
{
	struct fio_file *f;
	int ret;

	/*
	 * Not a special ipo
	 */
	if (ipo->ddir != DDIR_INVAL)
		return 0;

	f = td->files[ipo->fileno];

	switch (ipo->file_action) {
	case FIO_LOG_OPEN_FILE:
		ret = td_io_open_file(td, f);
		if (!ret) {
			free(ipo);
			break;
		}
		td_verror(td, ret, "iolog open file");
		return -1;
	case FIO_LOG_CLOSE_FILE:
		td_io_close_file(td, f);
		break;
	case FIO_LOG_UNLINK_FILE:
		unlink(f->file_name);
		break;
	default:
		log_err("fio: bad file action %d\n", ipo->file_action);
		break;
	}

	return 1;
}

int read_iolog_get(struct thread_data *td, struct io_u *io_u)
{
	struct io_piece *ipo;

	while (!list_empty(&td->io_log_list)) {
		int ret;

		ipo = list_entry(td->io_log_list.next, struct io_piece, list);
		list_del(&ipo->list);

		ret = ipo_special(td, ipo);
		if (ret < 0) {
			free(ipo);
			break;
		} else if (ret > 0) {
			free(ipo);
			continue;
		}

		io_u->offset = ipo->offset;
		io_u->buflen = ipo->len;
		io_u->ddir = ipo->ddir;
		io_u->file = td->files[ipo->fileno];
		get_file(io_u->file);

		dprint(FD_IO, "iolog: get %llu/%lu/%s\n", io_u->offset,
					io_u->buflen, io_u->file->file_name);

		if (ipo->delay)
			iolog_delay(td, ipo->delay);

		free(ipo);
		return 0;
	}

	td->done = 1;
	return 1;
}

void prune_io_piece_log(struct thread_data *td)
{
	struct io_piece *ipo;
	struct rb_node *n;

	while ((n = rb_first(&td->io_hist_tree)) != NULL) {
		ipo = rb_entry(n, struct io_piece, rb_node);
		rb_erase(n, &td->io_hist_tree);
		free(ipo);
	}

	while (!list_empty(&td->io_hist_list)) {
		ipo = list_entry(td->io_hist_list.next, struct io_piece, list);
		list_del(&ipo->list);
		free(ipo);
	}
}

/*
 * log a successful write, so we can unwind the log for verify
 */
void log_io_piece(struct thread_data *td, struct io_u *io_u)
{
	struct rb_node **p, *parent;
	struct io_piece *ipo, *__ipo;

	ipo = malloc(sizeof(struct io_piece));
	ipo->file = io_u->file;
	ipo->offset = io_u->offset;
	ipo->len = io_u->buflen;

	/*
	 * We don't need to sort the entries, if:
	 *
	 *	Sequential writes, or
	 *	Random writes that lay out the file as it goes along
	 *
	 * For both these cases, just reading back data in the order we
	 * wrote it out is the fastest.
	 */
	if (!td_random(td) || !td->o.overwrite) {
		INIT_LIST_HEAD(&ipo->list);
		list_add_tail(&ipo->list, &td->io_hist_list);
		return;
	}

	RB_CLEAR_NODE(&ipo->rb_node);
	p = &td->io_hist_tree.rb_node;
	parent = NULL;

	/*
	 * Sort the entry into the verification list
	 */
	while (*p) {
		parent = *p;

		__ipo = rb_entry(parent, struct io_piece, rb_node);
		if (ipo->offset <= __ipo->offset)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
	}

	rb_link_node(&ipo->rb_node, parent, p);
	rb_insert_color(&ipo->rb_node, &td->io_hist_tree);
}

void write_iolog_close(struct thread_data *td)
{
	fflush(td->iolog_f);
	fclose(td->iolog_f);
	free(td->iolog_buf);
	td->iolog_f = NULL;
	td->iolog_buf = NULL;
}

/*
 * Read version 2 iolog data. It is enhanced to include per-file logging,
 * syncs, etc.
 */
static int read_iolog2(struct thread_data *td, FILE *f)
{
	unsigned long long offset;
	unsigned int bytes;
	int reads, writes, fileno = 0, file_action = 0; /* stupid gcc */
	char *fname, *act;
	char *str, *p;
	enum fio_ddir rw;

	free_release_files(td);

	/*
	 * Read in the read iolog and store it, reuse the infrastructure
	 * for doing verifications.
	 */
	str = malloc(4096);
	fname = malloc(256+16);
	act = malloc(256+16);

	reads = writes = 0;
	while ((p = fgets(str, 4096, f)) != NULL) {
		struct io_piece *ipo;
		int r;

		r = sscanf(p, "%256s %256s %llu %u", fname, act, &offset,
									&bytes);
		if (r == 4) {
			/*
			 * Check action first
			 */
			if (!strcmp(act, "read"))
				rw = DDIR_READ;
			else if (!strcmp(act, "write"))
				rw = DDIR_WRITE;
			else if (!strcmp(act, "sync"))
				rw = DDIR_SYNC;
			else {
				log_err("fio: bad iolog file action: %s\n",
									act);
				continue;
			}
		} else if (r == 2) {
			rw = DDIR_INVAL;
			if (!strcmp(act, "add")) {
				td->o.nr_files++;
				fileno = add_file(td, fname);
				file_action = FIO_LOG_ADD_FILE;
				continue;
			} else if (!strcmp(act, "open")) {
				fileno = get_fileno(td, fname);
				file_action = FIO_LOG_OPEN_FILE;
			} else if (!strcmp(act, "close")) {
				fileno = get_fileno(td, fname);
				file_action = FIO_LOG_CLOSE_FILE;
			} else {
				log_err("fio: bad iolog file action: %s\n",
									act);
				continue;
			}
		} else {
			log_err("bad iolog2: %s", p);
			continue;
		}

		if (rw == DDIR_READ)
			reads++;
		else if (rw == DDIR_WRITE) {
			/*
			 * Don't add a write for ro mode
			 */
			if (read_only)
				continue;
			writes++;
		} else if (rw != DDIR_SYNC && rw != DDIR_INVAL) {
			log_err("bad ddir: %d\n", rw);
			continue;
		}

		/*
		 * Make note of file
		 */
		ipo = malloc(sizeof(*ipo));
		memset(ipo, 0, sizeof(*ipo));
		INIT_LIST_HEAD(&ipo->list);
		ipo->offset = offset;
		ipo->len = bytes;
		ipo->ddir = rw;
		if (bytes > td->o.max_bs[rw])
			td->o.max_bs[rw] = bytes;
		if (rw == DDIR_INVAL) {
			ipo->fileno = fileno;
			ipo->file_action = file_action;
		}
		queue_io_piece(td, ipo);
	}

	free(str);
	free(act);
	free(fname);

	if (writes && read_only) {
		log_err("fio: <%s> skips replay of %d writes due to"
			" read-only\n", td->o.name, writes);
		writes = 0;
	}

	if (!reads && !writes)
		return 1;
	else if (reads && !writes)
		td->o.td_ddir = TD_DDIR_READ;
	else if (!reads && writes)
		td->o.td_ddir = TD_DDIR_WRITE;
	else
		td->o.td_ddir = TD_DDIR_RW;

	return 0;
}

/*
 * open iolog, check version, and call appropriate parser
 */
static int init_iolog_read(struct thread_data *td)
{
	char buffer[256], *p;
	FILE *f;
	int ret;

	f = fopen(td->o.read_iolog_file, "r");
	if (!f) {
		perror("fopen read iolog");
		return 1;
	}

	p = fgets(buffer, sizeof(buffer), f);
	if (!p) {
		td_verror(td, errno, "iolog read");
		log_err("fio: unable to read iolog\n");
		return 1;
	}

	/*
	 * version 2 of the iolog stores a specific string as the
	 * first line, check for that
	 */
	if (!strncmp(iolog_ver2, buffer, strlen(iolog_ver2)))
		ret = read_iolog2(td, f);
	else {
		log_err("fio: iolog version 1 is no longer supported\n");
		ret = 1;
	}

	fclose(f);
	return ret;
}

/*
 * Setup a log for storing io patterns.
 */
static int init_iolog_write(struct thread_data *td)
{
	struct fio_file *ff;
	FILE *f;
	unsigned int i;

	f = fopen(td->o.write_iolog_file, "w+");
	if (!f) {
		perror("fopen write iolog");
		return 1;
	}

	/*
	 * That's it for writing, setup a log buffer and we're done.
	  */
	td->iolog_f = f;
	td->iolog_buf = malloc(8192);
	setvbuf(f, td->iolog_buf, _IOFBF, 8192);

	/*
	 * write our version line
	 */
	if (fprintf(f, "%s\n", iolog_ver2) < 0) {
		perror("iolog init\n");
		return 1;
	}

	/*
	 * add all known files
	 */
	for_each_file(td, ff, i)
		log_file(td, ff, FIO_LOG_ADD_FILE);

	return 0;
}

int init_iolog(struct thread_data *td)
{
	int ret = 0;

	if (td->io_ops->flags & FIO_DISKLESSIO)
		return 0;

	if (td->o.read_iolog_file) {
		/*
		 * Check if it's a blktrace file and load that if possible.
		 * Otherwise assume it's a normal log file and load that.
		 */
		if (is_blktrace(td->o.read_iolog_file))
			ret = load_blktrace(td, td->o.read_iolog_file);
		else
			ret = init_iolog_read(td);
	} else if (td->o.write_iolog_file)
		ret = init_iolog_write(td);

	return ret;
}

void setup_log(struct io_log **log)
{
	struct io_log *l = malloc(sizeof(*l));

	l->nr_samples = 0;
	l->max_samples = 1024;
	l->log = malloc(l->max_samples * sizeof(struct io_sample));
	*log = l;
}

void __finish_log(struct io_log *log, const char *name)
{
	unsigned int i;
	FILE *f;

	f = fopen(name, "w");
	if (!f) {
		perror("fopen log");
		return;
	}

	for (i = 0; i < log->nr_samples; i++) {
		fprintf(f, "%lu, %lu, %u\n", log->log[i].time, log->log[i].val,
						log->log[i].ddir);
	}

	fclose(f);
	free(log->log);
	free(log);
}

void finish_log(struct thread_data *td, struct io_log *log, const char *name)
{
	char file_name[256];

	snprintf(file_name, 200, "%s_%s.log", td->o.name, name);
	__finish_log(log, file_name);
}
Commit	Line	Data
	1	/*
	2	* Code related to writing an iolog of what a thread is doing, and to
	3	* later read that back and replay
	4	*/
	5	#include <stdio.h>
	6	#include <stdlib.h>
	7	#include <assert.h>
	8	#include "list.h"
	9	#include "fio.h"
	10
	11	static const char iolog_ver2[] = "fio version 2 iolog";
	12
	13	void queue_io_piece(struct thread_data td, struct io_piece ipo)
	14	{
	15	list_add_tail(&ipo->list, &td->io_log_list);
	16	td->total_io_size += ipo->len;
	17	}
	18
	19	void log_io_u(struct thread_data td, struct io_u io_u)
	20	{
	21	const char *act[] = { "read", "write", "sync" };
	22
	23	assert(io_u->ddir < 3);
	24
	25	if (!td->o.write_iolog_file)
	26	return;
	27
	28	fprintf(td->iolog_f, "%s %s %llu %lu\n", io_u->file->file_name,
	29	act[io_u->ddir], io_u->offset,
	30	io_u->buflen);
	31	}
	32
	33	void log_file(struct thread_data td, struct fio_file f,
	34	enum file_log_act what)
	35	{
	36	const char *act[] = { "add", "open", "close" };
	37
	38	assert(what < 3);
	39
	40	if (!td->o.write_iolog_file)
	41	return;
	42
	43	fprintf(td->iolog_f, "%s %s\n", f->file_name, act[what]);
	44	}
	45
	46	static void iolog_delay(struct thread_data *td, unsigned long delay)
	47	{
	48	unsigned long usec = utime_since_now(&td->last_issue);
	49
	50	if (delay < usec)
	51	return;
	52
	53	delay -= usec;
	54
	55	/*
	56	* less than 100 usec delay, just regard it as noise
	57	*/
	58	if (delay < 100)
	59	return;
	60
	61	usec_sleep(td, delay);
	62	}
	63
	64	static int ipo_special(struct thread_data td, struct io_piece ipo)
	65	{
	66	struct fio_file *f;
	67	int ret;
	68
	69	/*
	70	* Not a special ipo
	71	*/
	72	if (ipo->ddir != DDIR_INVAL)
	73	return 0;
	74
	75	f = td->files[ipo->fileno];
	76
	77	switch (ipo->file_action) {
	78	case FIO_LOG_OPEN_FILE:
	79	ret = td_io_open_file(td, f);
	80	if (!ret) {
	81	free(ipo);
	82	break;
	83	}
	84	td_verror(td, ret, "iolog open file");
	85	return -1;
	86	case FIO_LOG_CLOSE_FILE:
	87	td_io_close_file(td, f);
	88	break;
	89	case FIO_LOG_UNLINK_FILE:
	90	unlink(f->file_name);
	91	break;
	92	default:
	93	log_err("fio: bad file action %d\n", ipo->file_action);
	94	break;
	95	}
	96
	97	return 1;
	98	}
	99
	100	int read_iolog_get(struct thread_data td, struct io_u io_u)
	101	{
	102	struct io_piece *ipo;
	103
	104	while (!list_empty(&td->io_log_list)) {
	105	int ret;
	106
	107	ipo = list_entry(td->io_log_list.next, struct io_piece, list);
	108	list_del(&ipo->list);
	109
	110	ret = ipo_special(td, ipo);
	111	if (ret < 0) {
	112	free(ipo);
	113	break;
	114	} else if (ret > 0) {
	115	free(ipo);
	116	continue;
	117	}
	118
	119	io_u->offset = ipo->offset;
	120	io_u->buflen = ipo->len;
	121	io_u->ddir = ipo->ddir;
	122	io_u->file = td->files[ipo->fileno];
	123	get_file(io_u->file);
	124
	125	dprint(FD_IO, "iolog: get %llu/%lu/%s\n", io_u->offset,
	126	io_u->buflen, io_u->file->file_name);
	127
	128	if (ipo->delay)
	129	iolog_delay(td, ipo->delay);
	130
	131	free(ipo);
	132	return 0;
	133	}
	134
	135	td->done = 1;
	136	return 1;
	137	}
	138
	139	void prune_io_piece_log(struct thread_data *td)
	140	{
	141	struct io_piece *ipo;
	142	struct rb_node *n;
	143
	144	while ((n = rb_first(&td->io_hist_tree)) != NULL) {
	145	ipo = rb_entry(n, struct io_piece, rb_node);
	146	rb_erase(n, &td->io_hist_tree);
	147	free(ipo);
	148	}
	149
	150	while (!list_empty(&td->io_hist_list)) {
	151	ipo = list_entry(td->io_hist_list.next, struct io_piece, list);
	152	list_del(&ipo->list);
	153	free(ipo);
	154	}
	155	}
	156
	157	/*
	158	* log a successful write, so we can unwind the log for verify
	159	*/
	160	void log_io_piece(struct thread_data td, struct io_u io_u)
	161	{
	162	struct rb_node *p, parent;
	163	struct io_piece ipo, __ipo;
	164
	165	ipo = malloc(sizeof(struct io_piece));
	166	ipo->file = io_u->file;
	167	ipo->offset = io_u->offset;
	168	ipo->len = io_u->buflen;
	169
	170	/*
	171	* We don't need to sort the entries, if:
	172	*
	173	* Sequential writes, or
	174	* Random writes that lay out the file as it goes along
	175	*
	176	* For both these cases, just reading back data in the order we
	177	* wrote it out is the fastest.
	178	*/
	179	if (!td_random(td) \|\| !td->o.overwrite) {
	180	INIT_LIST_HEAD(&ipo->list);
	181	list_add_tail(&ipo->list, &td->io_hist_list);
	182	return;
	183	}
	184
	185	RB_CLEAR_NODE(&ipo->rb_node);
	186	p = &td->io_hist_tree.rb_node;
	187	parent = NULL;
	188
	189	/*
	190	* Sort the entry into the verification list
	191	*/
	192	while (*p) {
	193	parent = *p;
	194
	195	__ipo = rb_entry(parent, struct io_piece, rb_node);
	196	if (ipo->offset <= __ipo->offset)
	197	p = &(*p)->rb_left;
	198	else
	199	p = &(*p)->rb_right;
	200	}
	201
	202	rb_link_node(&ipo->rb_node, parent, p);
	203	rb_insert_color(&ipo->rb_node, &td->io_hist_tree);
	204	}
	205
	206	void write_iolog_close(struct thread_data *td)
	207	{
	208	fflush(td->iolog_f);
	209	fclose(td->iolog_f);
	210	free(td->iolog_buf);
	211	td->iolog_f = NULL;
	212	td->iolog_buf = NULL;
	213	}
	214
	215	/*
	216	* Read version 2 iolog data. It is enhanced to include per-file logging,
	217	* syncs, etc.
	218	*/
	219	static int read_iolog2(struct thread_data td, FILE f)
	220	{
	221	unsigned long long offset;
	222	unsigned int bytes;
	223	int reads, writes, fileno = 0, file_action = 0; /* stupid gcc */
	224	char fname, act;
	225	char str, p;
	226	enum fio_ddir rw;
	227
	228	free_release_files(td);
	229
	230	/*
	231	* Read in the read iolog and store it, reuse the infrastructure
	232	* for doing verifications.
	233	*/
	234	str = malloc(4096);
	235	fname = malloc(256+16);
	236	act = malloc(256+16);
	237
	238	reads = writes = 0;
	239	while ((p = fgets(str, 4096, f)) != NULL) {
	240	struct io_piece *ipo;
	241	int r;
	242
	243	r = sscanf(p, "%256s %256s %llu %u", fname, act, &offset,
	244	&bytes);
	245	if (r == 4) {
	246	/*
	247	* Check action first
	248	*/
	249	if (!strcmp(act, "read"))
	250	rw = DDIR_READ;
	251	else if (!strcmp(act, "write"))
	252	rw = DDIR_WRITE;
	253	else if (!strcmp(act, "sync"))
	254	rw = DDIR_SYNC;
	255	else {
	256	log_err("fio: bad iolog file action: %s\n",
	257	act);
	258	continue;
	259	}
	260	} else if (r == 2) {
	261	rw = DDIR_INVAL;
	262	if (!strcmp(act, "add")) {
	263	td->o.nr_files++;
	264	fileno = add_file(td, fname);
	265	file_action = FIO_LOG_ADD_FILE;
	266	continue;
	267	} else if (!strcmp(act, "open")) {
	268	fileno = get_fileno(td, fname);
	269	file_action = FIO_LOG_OPEN_FILE;
	270	} else if (!strcmp(act, "close")) {
	271	fileno = get_fileno(td, fname);
	272	file_action = FIO_LOG_CLOSE_FILE;
	273	} else {
	274	log_err("fio: bad iolog file action: %s\n",
	275	act);
	276	continue;
	277	}
	278	} else {
	279	log_err("bad iolog2: %s", p);
	280	continue;
	281	}
	282
	283	if (rw == DDIR_READ)
	284	reads++;
	285	else if (rw == DDIR_WRITE) {
	286	/*
	287	* Don't add a write for ro mode
	288	*/
	289	if (read_only)
	290	continue;
	291	writes++;
	292	} else if (rw != DDIR_SYNC && rw != DDIR_INVAL) {
	293	log_err("bad ddir: %d\n", rw);
	294	continue;
	295	}
	296
	297	/*
	298	* Make note of file
	299	*/
	300	ipo = malloc(sizeof(*ipo));
	301	memset(ipo, 0, sizeof(*ipo));
	302	INIT_LIST_HEAD(&ipo->list);
	303	ipo->offset = offset;
	304	ipo->len = bytes;
	305	ipo->ddir = rw;
	306	if (bytes > td->o.max_bs[rw])
	307	td->o.max_bs[rw] = bytes;
	308	if (rw == DDIR_INVAL) {
	309	ipo->fileno = fileno;
	310	ipo->file_action = file_action;
	311	}
	312	queue_io_piece(td, ipo);
	313	}
	314
	315	free(str);
	316	free(act);
	317	free(fname);
	318
	319	if (writes && read_only) {
	320	log_err("fio: <%s> skips replay of %d writes due to"
	321	" read-only\n", td->o.name, writes);
	322	writes = 0;
	323	}
	324
	325	if (!reads && !writes)
	326	return 1;
	327	else if (reads && !writes)
	328	td->o.td_ddir = TD_DDIR_READ;
	329	else if (!reads && writes)
	330	td->o.td_ddir = TD_DDIR_WRITE;
	331	else
	332	td->o.td_ddir = TD_DDIR_RW;
	333
	334	return 0;
	335	}
	336
	337	/*
	338	* open iolog, check version, and call appropriate parser
	339	*/
	340	static int init_iolog_read(struct thread_data *td)
	341	{
	342	char buffer[256], *p;
	343	FILE *f;
	344	int ret;
	345
	346	f = fopen(td->o.read_iolog_file, "r");
	347	if (!f) {
	348	perror("fopen read iolog");
	349	return 1;
	350	}
	351
	352	p = fgets(buffer, sizeof(buffer), f);
	353	if (!p) {
	354	td_verror(td, errno, "iolog read");
	355	log_err("fio: unable to read iolog\n");
	356	return 1;
	357	}
	358
	359	/*
	360	* version 2 of the iolog stores a specific string as the
	361	* first line, check for that
	362	*/
	363	if (!strncmp(iolog_ver2, buffer, strlen(iolog_ver2)))
	364	ret = read_iolog2(td, f);
	365	else {
	366	log_err("fio: iolog version 1 is no longer supported\n");
	367	ret = 1;
	368	}
	369
	370	fclose(f);
	371	return ret;
	372	}
	373
	374	/*
	375	* Setup a log for storing io patterns.
	376	*/
	377	static int init_iolog_write(struct thread_data *td)
	378	{
	379	struct fio_file *ff;
	380	FILE *f;
	381	unsigned int i;
	382
	383	f = fopen(td->o.write_iolog_file, "w+");
	384	if (!f) {
	385	perror("fopen write iolog");
	386	return 1;
	387	}
	388
	389	/*
	390	* That's it for writing, setup a log buffer and we're done.
	391	*/
	392	td->iolog_f = f;
	393	td->iolog_buf = malloc(8192);
	394	setvbuf(f, td->iolog_buf, _IOFBF, 8192);
	395
	396	/*
	397	* write our version line
	398	*/
	399	if (fprintf(f, "%s\n", iolog_ver2) < 0) {
	400	perror("iolog init\n");
	401	return 1;
	402	}
	403
	404	/*
	405	* add all known files
	406	*/
	407	for_each_file(td, ff, i)
	408	log_file(td, ff, FIO_LOG_ADD_FILE);
	409
	410	return 0;
	411	}
	412
	413	int init_iolog(struct thread_data *td)
	414	{
	415	int ret = 0;
	416
	417	if (td->io_ops->flags & FIO_DISKLESSIO)
	418	return 0;
	419
	420	if (td->o.read_iolog_file) {
	421	/*
	422	* Check if it's a blktrace file and load that if possible.
	423	* Otherwise assume it's a normal log file and load that.
	424	*/
	425	if (is_blktrace(td->o.read_iolog_file))
	426	ret = load_blktrace(td, td->o.read_iolog_file);
	427	else
	428	ret = init_iolog_read(td);
	429	} else if (td->o.write_iolog_file)
	430	ret = init_iolog_write(td);
	431
	432	return ret;
	433	}
	434
	435	void setup_log(struct io_log **log)
	436	{
	437	struct io_log l = malloc(sizeof(l));
	438
	439	l->nr_samples = 0;
	440	l->max_samples = 1024;
	441	l->log = malloc(l->max_samples * sizeof(struct io_sample));
	442	*log = l;
	443	}
	444
	445	void __finish_log(struct io_log log, const char name)
	446	{
	447	unsigned int i;
	448	FILE *f;
	449
	450	f = fopen(name, "w");
	451	if (!f) {
	452	perror("fopen log");
	453	return;
	454	}
	455
	456	for (i = 0; i < log->nr_samples; i++) {
	457	fprintf(f, "%lu, %lu, %u\n", log->log[i].time, log->log[i].val,
	458	log->log[i].ddir);
	459	}
	460
	461	fclose(f);
	462	free(log->log);
	463	free(log);
	464	}
	465
	466	void finish_log(struct thread_data td, struct io_log log, const char *name)
	467	{
	468	char file_name[256];
	469
	470	snprintf(file_name, 200, "%s_%s.log", td->o.name, name);
	471	__finish_log(log, file_name);
	472	}