log.c - platform/external/fio - Gitiles

 /*
  * 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 <libgen.h>
 #include <assert.h>
 #include "flist.h"
 #include "fio.h"
 #include "verify.h"

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

 void queue_io_piece(struct thread_data *td, struct io_piece *ipo)
 {
 	flist_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", "datasync",
 				"sync_file_range" };

 	assert(io_u->ddir <= 4);

 	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;


 	/*
 	 * this happens on the pre-open/close done before the job starts
 	 */
 	if (!td->iolog_f)
 		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)
 			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;
 	unsigned long elapsed;

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

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

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

 		io_u->ddir = ipo->ddir;
 		if (ipo->ddir != DDIR_WAIT) {
 			io_u->offset = ipo->offset;
 			io_u->buflen = ipo->len;
 			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);
 		} else {
 			elapsed = mtime_since_genesis();
 			if (ipo->delay > elapsed)
 				usec_sleep(td, (ipo->delay - elapsed) * 1000);

 		}

 		free(ipo);

 		if (ipo->ddir != DDIR_WAIT)
 			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);
 		td->io_hist_len--;
 		free(ipo);
 	}

 	while (!flist_empty(&td->io_hist_list)) {
 		ipo = flist_entry(td->io_hist_list.next, struct io_piece, list);
 		flist_del(&ipo->list);
 		td->io_hist_len--;
 		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.
 	 *
 	 * One exception is if we don't have a random map AND we are doing
 	 * verifies, in that case we need to check for duplicate blocks and
 	 * drop the old one, which we rely on the rb insert/lookup for
 	 * handling.
 	 */
 	if ((!td_random(td) || !td->o.overwrite) &&
 	      (file_randommap(td, ipo->file) || td->o.verify == VERIFY_NONE)) {
 		INIT_FLIST_HEAD(&ipo->list);
 		flist_add_tail(&ipo->list, &td->io_hist_list);
 		td->io_hist_len++;
 		return;
 	}

 	RB_CLEAR_NODE(&ipo->rb_node);

 	/*
 	 * Sort the entry into the verification list
 	 */
 restart:
 	p = &td->io_hist_tree.rb_node;
 	parent = NULL;
 	while (*p) {
 		parent = *p;

 		__ipo = rb_entry(parent, struct io_piece, rb_node);
 		if (ipo->file < __ipo->file)
 			p = &(*p)->rb_left;
 		else if (ipo->file > __ipo->file)
 			p = &(*p)->rb_right;
 		else if (ipo->offset < __ipo->offset)
 			p = &(*p)->rb_left;
 		else if (ipo->offset > __ipo->offset)
 			p = &(*p)->rb_right;
 		else {
 			assert(ipo->len == __ipo->len);
 			td->io_hist_len--;
 			rb_erase(parent, &td->io_hist_tree);
 			goto restart;
 		}
 	}

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

 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, waits, 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 = waits = 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, "wait"))
 				rw = DDIR_WAIT;
 			else if (!strcmp(act, "read"))
 				rw = DDIR_READ;
 			else if (!strcmp(act, "write"))
 				rw = DDIR_WRITE;
 			else if (!strcmp(act, "sync"))
 				rw = DDIR_SYNC;
 			else if (!strcmp(act, "datasync"))
 				rw = DDIR_DATASYNC;
 			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_WAIT) {
 			waits++;
 		} else if (rw == DDIR_INVAL) {
 		} else if (!ddir_sync(rw)) {
 			log_err("bad ddir: %d\n", rw);
 			continue;
 		}

 		/*
 		 * Make note of file
 		 */
 		ipo = malloc(sizeof(*ipo));
 		memset(ipo, 0, sizeof(*ipo));
 		INIT_FLIST_HEAD(&ipo->list);
 		ipo->ddir = rw;
 		if (rw == DDIR_WAIT) {
 			ipo->delay = offset;
 		} else {
 			ipo->offset = offset;
 			ipo->len = bytes;
 			if (bytes > td->o.max_bs[rw])
 				td->o.max_bs[rw] = bytes;
 			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 && !waits)
 		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, "a");
 	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->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, "a");
 	if (!f) {
 		perror("fopen log");
 		return;
 	}

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

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

 void finish_log_named(struct thread_data *td, struct io_log *log,
 		       const char *prefix, const char *postfix)
 {
 	char file_name[256], *p;

 	snprintf(file_name, 200, "%s_%s.log", prefix, postfix);
 	p = basename(file_name);
 	__finish_log(log, p);
 }

 void finish_log(struct thread_data *td, struct io_log *log, const char *name)
 {
 	finish_log_named(td, log, td->o.name, name);
 }
	/*
	* 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 <libgen.h>
	#include <assert.h>
	#include "flist.h"
	#include "fio.h"
	#include "verify.h"

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

	void queue_io_piece(struct thread_data td, struct io_piece ipo)
	{
	flist_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", "datasync",
	"sync_file_range" };

	assert(io_u->ddir <= 4);

	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;


	/*
	* this happens on the pre-open/close done before the job starts
	*/
	if (!td->iolog_f)
	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)
	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;
	unsigned long elapsed;

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

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

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

	io_u->ddir = ipo->ddir;
	if (ipo->ddir != DDIR_WAIT) {
	io_u->offset = ipo->offset;
	io_u->buflen = ipo->len;
	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);
	} else {
	elapsed = mtime_since_genesis();
	if (ipo->delay > elapsed)
	usec_sleep(td, (ipo->delay - elapsed) * 1000);

	}

	free(ipo);

	if (ipo->ddir != DDIR_WAIT)
	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);
	td->io_hist_len--;
	free(ipo);
	}

	while (!flist_empty(&td->io_hist_list)) {
	ipo = flist_entry(td->io_hist_list.next, struct io_piece, list);
	flist_del(&ipo->list);
	td->io_hist_len--;
	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.
	*
	* One exception is if we don't have a random map AND we are doing
	* verifies, in that case we need to check for duplicate blocks and
	* drop the old one, which we rely on the rb insert/lookup for
	* handling.
	*/
	if ((!td_random(td) \|\| !td->o.overwrite) &&
	(file_randommap(td, ipo->file) \|\| td->o.verify == VERIFY_NONE)) {
	INIT_FLIST_HEAD(&ipo->list);
	flist_add_tail(&ipo->list, &td->io_hist_list);
	td->io_hist_len++;
	return;
	}

	RB_CLEAR_NODE(&ipo->rb_node);

	/*
	* Sort the entry into the verification list
	*/
	restart:
	p = &td->io_hist_tree.rb_node;
	parent = NULL;
	while (*p) {
	parent = *p;

	__ipo = rb_entry(parent, struct io_piece, rb_node);
	if (ipo->file < __ipo->file)
	p = &(*p)->rb_left;
	else if (ipo->file > __ipo->file)
	p = &(*p)->rb_right;
	else if (ipo->offset < __ipo->offset)
	p = &(*p)->rb_left;
	else if (ipo->offset > __ipo->offset)
	p = &(*p)->rb_right;
	else {
	assert(ipo->len == __ipo->len);
	td->io_hist_len--;
	rb_erase(parent, &td->io_hist_tree);
	goto restart;
	}
	}

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

	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, waits, 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 = waits = 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, "wait"))
	rw = DDIR_WAIT;
	else if (!strcmp(act, "read"))
	rw = DDIR_READ;
	else if (!strcmp(act, "write"))
	rw = DDIR_WRITE;
	else if (!strcmp(act, "sync"))
	rw = DDIR_SYNC;
	else if (!strcmp(act, "datasync"))
	rw = DDIR_DATASYNC;
	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_WAIT) {
	waits++;
	} else if (rw == DDIR_INVAL) {
	} else if (!ddir_sync(rw)) {
	log_err("bad ddir: %d\n", rw);
	continue;
	}

	/*
	* Make note of file
	*/
	ipo = malloc(sizeof(*ipo));
	memset(ipo, 0, sizeof(*ipo));
	INIT_FLIST_HEAD(&ipo->list);
	ipo->ddir = rw;
	if (rw == DDIR_WAIT) {
	ipo->delay = offset;
	} else {
	ipo->offset = offset;
	ipo->len = bytes;
	if (bytes > td->o.max_bs[rw])
	td->o.max_bs[rw] = bytes;
	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 && !waits)
	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, "a");
	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->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, "a");
	if (!f) {
	perror("fopen log");
	return;
	}

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

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

	void finish_log_named(struct thread_data td, struct io_log log,
	const char prefix, const char postfix)
	{
	char file_name[256], *p;

	snprintf(file_name, 200, "%s_%s.log", prefix, postfix);
	p = basename(file_name);
	__finish_log(log, p);
	}

	void finish_log(struct thread_data td, struct io_log log, const char *name)
	{
	finish_log_named(td, log, td->o.name, name);
	}