diskutil.c - fp2-dev/platform/external/fio - Gitiles

 #include <stdio.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <dirent.h>
 #include <libgen.h>
 #include <math.h>

 #include "fio.h"
 #include "smalloc.h"
 #include "diskutil.h"

 static int last_majdev, last_mindev;
 static struct disk_util *last_du;

 static struct flist_head disk_list = FLIST_HEAD_INIT(disk_list);

 static struct disk_util *__init_per_file_disk_util(struct thread_data *td,
 		int majdev, int mindev, char *path);

 static void disk_util_free(struct disk_util *du)
 {
 	if (du == last_du)
 		last_du = NULL;

 	while (!flist_empty(&du->slaves)) {
 		struct disk_util *slave;

 		slave = flist_entry(du->slaves.next, struct disk_util, slavelist);
 		flist_del(&slave->slavelist);
 		slave->users--;
 	}

 	fio_mutex_remove(du->lock);
 	sfree(du->name);
 	sfree(du);
 }

 static int get_io_ticks(struct disk_util *du, struct disk_util_stat *dus)
 {
 	unsigned in_flight;
 	char line[256];
 	FILE *f;
 	char *p;
 	int ret;

 	dprint(FD_DISKUTIL, "open stat file: %s\n", du->path);

 	f = fopen(du->path, "r");
 	if (!f)
 		return 1;

 	p = fgets(line, sizeof(line), f);
 	if (!p) {
 		fclose(f);
 		return 1;
 	}

 	dprint(FD_DISKUTIL, "%s: %s", du->path, p);

 	ret = sscanf(p, "%u %u %llu %u %u %u %llu %u %u %u %u\n", &dus->ios[0],
 					&dus->merges[0], &dus->sectors[0],
 					&dus->ticks[0], &dus->ios[1],
 					&dus->merges[1], &dus->sectors[1],
 					&dus->ticks[1], &in_flight,
 					&dus->io_ticks, &dus->time_in_queue);
 	fclose(f);
 	dprint(FD_DISKUTIL, "%s: stat read ok? %d\n", du->path, ret == 1);
 	return ret != 11;
 }

 static void update_io_tick_disk(struct disk_util *du)
 {
 	struct disk_util_stat __dus, *dus, *ldus;
 	struct timeval t;

 	if (!du->users)
 		return;
 	if (get_io_ticks(du, &__dus))
 		return;

 	dus = &du->dus;
 	ldus = &du->last_dus;

 	dus->sectors[0] += (__dus.sectors[0] - ldus->sectors[0]);
 	dus->sectors[1] += (__dus.sectors[1] - ldus->sectors[1]);
 	dus->ios[0] += (__dus.ios[0] - ldus->ios[0]);
 	dus->ios[1] += (__dus.ios[1] - ldus->ios[1]);
 	dus->merges[0] += (__dus.merges[0] - ldus->merges[0]);
 	dus->merges[1] += (__dus.merges[1] - ldus->merges[1]);
 	dus->ticks[0] += (__dus.ticks[0] - ldus->ticks[0]);
 	dus->ticks[1] += (__dus.ticks[1] - ldus->ticks[1]);
 	dus->io_ticks += (__dus.io_ticks - ldus->io_ticks);
 	dus->time_in_queue += (__dus.time_in_queue - ldus->time_in_queue);

 	fio_gettime(&t, NULL);
 	du->msec += mtime_since(&du->time, &t);
 	memcpy(&du->time, &t, sizeof(t));
 	memcpy(ldus, &__dus, sizeof(__dus));
 }

 void update_io_ticks(void)
 {
 	struct flist_head *entry;
 	struct disk_util *du;

 	dprint(FD_DISKUTIL, "update io ticks\n");

 	flist_for_each(entry, &disk_list) {
 		du = flist_entry(entry, struct disk_util, list);
 		update_io_tick_disk(du);
 	}
 }

 static struct disk_util *disk_util_exists(int major, int minor)
 {
 	struct flist_head *entry;
 	struct disk_util *du;

 	flist_for_each(entry, &disk_list) {
 		du = flist_entry(entry, struct disk_util, list);

 		if (major == du->major && minor == du->minor)
 			return du;
 	}

 	return NULL;
 }

 static int get_device_numbers(char *file_name, int *maj, int *min)
 {
 	struct stat st;
 	int majdev, mindev;
 	char tempname[PATH_MAX], *p;

 	if (!lstat(file_name, &st)) {
 		if (S_ISBLK(st.st_mode)) {
 			majdev = major(st.st_rdev);
 			mindev = minor(st.st_rdev);
 		} else if (S_ISCHR(st.st_mode)) {
 			majdev = major(st.st_rdev);
 			mindev = minor(st.st_rdev);
 			if (fio_lookup_raw(st.st_rdev, &majdev, &mindev))
 				return -1;
 		} else if (S_ISFIFO(st.st_mode))
 			return -1;
 		else {
 			majdev = major(st.st_dev);
 			mindev = minor(st.st_dev);
 		}
 	} else {
 		/*
 		 * must be a file, open "." in that path
 		 */
 		strncpy(tempname, file_name, PATH_MAX - 1);
 		p = dirname(tempname);
 		if (stat(p, &st)) {
 			perror("disk util stat");
 			return -1;
 		}

 		majdev = major(st.st_dev);
 		mindev = minor(st.st_dev);
 	}

 	*min = mindev;
 	*maj = majdev;

 	return 0;
 }

 static int read_block_dev_entry(char *path, int *maj, int *min)
 {
 	char line[256], *p;
 	FILE *f;

 	f = fopen(path, "r");
 	if (!f) {
 		perror("open path");
 		return 1;
 	}

 	p = fgets(line, sizeof(line), f);
 	fclose(f);

 	if (!p)
 		return 1;

 	if (sscanf(p, "%u:%u", maj, min) != 2)
 		return 1;

 	return 0;
 }

 static void find_add_disk_slaves(struct thread_data *td, char *path,
 				 struct disk_util *masterdu)
 {
 	DIR *dirhandle = NULL;
 	struct dirent *dirent = NULL;
 	char slavesdir[PATH_MAX], temppath[PATH_MAX], slavepath[PATH_MAX];
 	struct disk_util *slavedu = NULL;
 	int majdev, mindev;
 	ssize_t linklen;

 	sprintf(slavesdir, "%s/%s", path, "slaves");
 	dirhandle = opendir(slavesdir);
 	if (!dirhandle)
 		return;

 	while ((dirent = readdir(dirhandle)) != NULL) {
 		if (!strcmp(dirent->d_name, ".") ||
 		    !strcmp(dirent->d_name, ".."))
 			continue;

 		sprintf(temppath, "%s/%s", slavesdir, dirent->d_name);
 		/* Can we always assume that the slaves device entries
 		 * are links to the real directories for the slave
 		 * devices?
 		 */
 		linklen = readlink(temppath, slavepath, PATH_MAX - 0);
 		if (linklen  < 0) {
 			perror("readlink() for slave device.");
 			return;
 		}
 		slavepath[linklen] = '\0';

 		sprintf(temppath, "%s/%s/dev", slavesdir, slavepath);
 		if (read_block_dev_entry(temppath, &majdev, &mindev)) {
 			perror("Error getting slave device numbers.");
 			return;
 		}

 		/*
 		 * See if this maj,min already exists
 		 */
 		slavedu = disk_util_exists(majdev, mindev);
 		if (slavedu)
 			continue;

 		sprintf(temppath, "%s/%s", slavesdir, slavepath);
 		__init_per_file_disk_util(td, majdev, mindev, temppath);
 		slavedu = disk_util_exists(majdev, mindev);

 		/* Should probably use an assert here. slavedu should
 		 * always be present at this point. */
 		if (slavedu) {
 			slavedu->users++;
 			flist_add_tail(&slavedu->slavelist, &masterdu->slaves);
 		}
 	}

 	closedir(dirhandle);
 }

 static struct disk_util *disk_util_add(struct thread_data * td, int majdev,
 				       int mindev, char *path)
 {
 	struct disk_util *du, *__du;
 	struct flist_head *entry;

 	dprint(FD_DISKUTIL, "add maj/min %d/%d: %s\n", majdev, mindev, path);

 	du = smalloc(sizeof(*du));
 	memset(du, 0, sizeof(*du));
 	INIT_FLIST_HEAD(&du->list);
 	sprintf(du->path, "%s/stat", path);
 	du->name = smalloc_strdup(basename(path));
 	du->sysfs_root = path;
 	du->major = majdev;
 	du->minor = mindev;
 	INIT_FLIST_HEAD(&du->slavelist);
 	INIT_FLIST_HEAD(&du->slaves);
 	du->lock = fio_mutex_init(1);
 	du->users = 0;

 	flist_for_each(entry, &disk_list) {
 		__du = flist_entry(entry, struct disk_util, list);

 		dprint(FD_DISKUTIL, "found %s in list\n", __du->name);

 		if (!strcmp(du->name, __du->name)) {
 			disk_util_free(du);
 			return __du;
 		}
 	}

 	dprint(FD_DISKUTIL, "add %s to list\n", du->name);

 	fio_gettime(&du->time, NULL);
 	get_io_ticks(du, &du->last_dus);

 	flist_add_tail(&du->list, &disk_list);
 	find_add_disk_slaves(td, path, du);
 	return du;
 }

 static int check_dev_match(int majdev, int mindev, char *path)
 {
 	int major, minor;

 	if (read_block_dev_entry(path, &major, &minor))
 		return 1;

 	if (majdev == major && mindev == minor)
 		return 0;

 	return 1;
 }

 static int find_block_dir(int majdev, int mindev, char *path, int link_ok)
 {
 	struct dirent *dir;
 	struct stat st;
 	int found = 0;
 	DIR *D;

 	D = opendir(path);
 	if (!D)
 		return 0;

 	while ((dir = readdir(D)) != NULL) {
 		char full_path[256];

 		if (!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, ".."))
 			continue;

 		sprintf(full_path, "%s/%s", path, dir->d_name);

 		if (!strcmp(dir->d_name, "dev")) {
 			if (!check_dev_match(majdev, mindev, full_path)) {
 				found = 1;
 				break;
 			}
 		}

 		if (link_ok) {
 			if (stat(full_path, &st) == -1) {
 				perror("stat");
 				break;
 			}
 		} else {
 			if (lstat(full_path, &st) == -1) {
 				perror("stat");
 				break;
 			}
 		}

 		if (!S_ISDIR(st.st_mode) || S_ISLNK(st.st_mode))
 			continue;

 		found = find_block_dir(majdev, mindev, full_path, 0);
 		if (found) {
 			strcpy(path, full_path);
 			break;
 		}
 	}

 	closedir(D);
 	return found;
 }

 static struct disk_util *__init_per_file_disk_util(struct thread_data *td,
 						   int majdev, int mindev,
 						   char *path)
 {
 	struct stat st;
 	char tmp[PATH_MAX];
 	char *p;

 	/*
 	 * If there's a ../queue/ directory there, we are inside a partition.
 	 * Check if that is the case and jump back. For loop/md/dm etc we
 	 * are already in the right spot.
 	 */
 	sprintf(tmp, "%s/../queue", path);
 	if (!stat(tmp, &st)) {
 		p = dirname(path);
 		sprintf(tmp, "%s/queue", p);
 		if (stat(tmp, &st)) {
 			log_err("unknown sysfs layout\n");
 			return NULL;
 		}
 		strncpy(tmp, p, PATH_MAX - 1);
 		sprintf(path, "%s", tmp);
 	}

 	if (td->o.ioscheduler && !td->sysfs_root)
 		td->sysfs_root = strdup(path);

 	return disk_util_add(td, majdev, mindev, path);
 }

 static struct disk_util *init_per_file_disk_util(struct thread_data *td,
 						 char *filename)
 {

 	char foo[PATH_MAX];
 	struct disk_util *du;
 	int mindev, majdev;

 	if (get_device_numbers(filename, &majdev, &mindev))
 		return NULL;

 	dprint(FD_DISKUTIL, "%s belongs to maj/min %d/%d\n", filename, majdev,
 			mindev);

 	du = disk_util_exists(majdev, mindev);
 	if (du) {
 		if (td->o.ioscheduler && !td->sysfs_root)
 			td->sysfs_root = strdup(du->sysfs_root);

 		return du;
 	}

 	/*
 	 * for an fs without a device, we will repeatedly stat through
 	 * sysfs which can take oodles of time for thousands of files. so
 	 * cache the last lookup and compare with that before going through
 	 * everything again.
 	 */
 	if (mindev == last_mindev && majdev == last_majdev)
 		return last_du;

 	last_mindev = mindev;
 	last_majdev = majdev;

 	sprintf(foo, "/sys/block");
 	if (!find_block_dir(majdev, mindev, foo, 1))
 		return NULL;

 	return __init_per_file_disk_util(td, majdev, mindev, foo);
 }

 static struct disk_util *__init_disk_util(struct thread_data *td,
 					  struct fio_file *f)
 {
 	return init_per_file_disk_util(td, f->file_name);
 }

 void init_disk_util(struct thread_data *td)
 {
 	struct fio_file *f;
 	unsigned int i;

 	if (!td->o.do_disk_util ||
 	    (td->io_ops->flags & (FIO_DISKLESSIO | FIO_NODISKUTIL)))
 		return;

 	for_each_file(td, f, i)
 		f->du = __init_disk_util(td, f);
 }

 static void aggregate_slaves_stats(struct disk_util *masterdu)
 {
 	struct disk_util_stat *dus;
 	struct flist_head *entry;
 	struct disk_util *slavedu;
 	double util, max_util = 0;
 	int slavecount = 0;

 	unsigned merges[2] = { 0, };
 	unsigned ticks[2] = { 0, };
 	unsigned time_in_queue = { 0, };
 	unsigned long long sectors[2] = { 0, };
 	unsigned ios[2] = { 0, };

 	flist_for_each(entry, &masterdu->slaves) {
 		slavedu = flist_entry(entry, struct disk_util, slavelist);
 		dus = &slavedu->dus;
 		ios[0] += dus->ios[0];
 		ios[1] += dus->ios[1];
 		merges[0] += dus->merges[0];
 		merges[1] += dus->merges[1];
 		sectors[0] += dus->sectors[0];
 		sectors[1] += dus->sectors[1];
 		ticks[0] += dus->ticks[0];
 		ticks[1] += dus->ticks[1];
 		time_in_queue += dus->time_in_queue;
 		++slavecount;

 		util = (double) (100 * dus->io_ticks / (double) slavedu->msec);
 		/* System utilization is the utilization of the
 		 * component with the highest utilization.
 		 */
 		if (util > max_util)
 			max_util = util;

 	}

 	if (max_util > 100.0)
 		max_util = 100.0;

 	log_info(", aggrios=%u/%u, aggrmerge=%u/%u, aggrticks=%u/%u,"
 			" aggrin_queue=%u, aggrutil=%3.2f%%",
 			ios[0]/slavecount, ios[1]/slavecount,
 			merges[0]/slavecount, merges[1]/slavecount,
 			ticks[0]/slavecount, ticks[1]/slavecount,
 			time_in_queue/slavecount, max_util);

 }

 void show_disk_util(void)
 {
 	struct disk_util_stat *dus;
 	struct flist_head *entry, *next;
 	struct disk_util *du;
 	double util;

 	if (flist_empty(&disk_list))
 		return;

 	log_info("\nDisk stats (read/write):\n");

 	flist_for_each(entry, &disk_list) {
 		du = flist_entry(entry, struct disk_util, list);
 		dus = &du->dus;

 		util = (double) 100 * du->dus.io_ticks / (double) du->msec;
 		if (util > 100.0)
 			util = 100.0;

 		/* If this node is the slave of a master device, as
 		 * happens in case of software RAIDs, inward-indent
 		 * this stats line to reflect a master-slave
 		 * relationship. Because the master device gets added
 		 * before the slave devices, we can safely assume that
 		 * the master's stats line has been displayed in a
 		 * previous iteration of this loop.
 		 */
 		if (!flist_empty(&du->slavelist))
 			log_info("  ");

 		log_info("  %s: ios=%u/%u, merge=%u/%u, ticks=%u/%u, "
 			 "in_queue=%u, util=%3.2f%%", du->name,
 						dus->ios[0], dus->ios[1],
 						dus->merges[0], dus->merges[1],
 						dus->ticks[0], dus->ticks[1],
 						dus->time_in_queue, util);

 		/* If the device has slaves, aggregate the stats for
 		 * those slave devices also.
 		 */
 		if (!flist_empty(&du->slaves))
 			aggregate_slaves_stats(du);

 		log_info("\n");
 	}

 	/*
 	 * now free the list
 	 */
 	flist_for_each_safe(entry, next, &disk_list) {
 		flist_del(entry);
 		du = flist_entry(entry, struct disk_util, list);
 		disk_util_free(du);
 	}
 }
	#include <stdio.h>
	#include <string.h>
	#include <sys/time.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <dirent.h>
	#include <libgen.h>
	#include <math.h>

	#include "fio.h"
	#include "smalloc.h"
	#include "diskutil.h"

	static int last_majdev, last_mindev;
	static struct disk_util *last_du;

	static struct flist_head disk_list = FLIST_HEAD_INIT(disk_list);

	static struct disk_util __init_per_file_disk_util(struct thread_data td,
	int majdev, int mindev, char *path);

	static void disk_util_free(struct disk_util *du)
	{
	if (du == last_du)
	last_du = NULL;

	while (!flist_empty(&du->slaves)) {
	struct disk_util *slave;

	slave = flist_entry(du->slaves.next, struct disk_util, slavelist);
	flist_del(&slave->slavelist);
	slave->users--;
	}

	fio_mutex_remove(du->lock);
	sfree(du->name);
	sfree(du);
	}

	static int get_io_ticks(struct disk_util du, struct disk_util_stat dus)
	{
	unsigned in_flight;
	char line[256];
	FILE *f;
	char *p;
	int ret;

	dprint(FD_DISKUTIL, "open stat file: %s\n", du->path);

	f = fopen(du->path, "r");
	if (!f)
	return 1;

	p = fgets(line, sizeof(line), f);
	if (!p) {
	fclose(f);
	return 1;
	}

	dprint(FD_DISKUTIL, "%s: %s", du->path, p);

	ret = sscanf(p, "%u %u %llu %u %u %u %llu %u %u %u %u\n", &dus->ios[0],
	&dus->merges[0], &dus->sectors[0],
	&dus->ticks[0], &dus->ios[1],
	&dus->merges[1], &dus->sectors[1],
	&dus->ticks[1], &in_flight,
	&dus->io_ticks, &dus->time_in_queue);
	fclose(f);
	dprint(FD_DISKUTIL, "%s: stat read ok? %d\n", du->path, ret == 1);
	return ret != 11;
	}

	static void update_io_tick_disk(struct disk_util *du)
	{
	struct disk_util_stat __dus, dus, ldus;
	struct timeval t;

	if (!du->users)
	return;
	if (get_io_ticks(du, &__dus))
	return;

	dus = &du->dus;
	ldus = &du->last_dus;

	dus->sectors[0] += (__dus.sectors[0] - ldus->sectors[0]);
	dus->sectors[1] += (__dus.sectors[1] - ldus->sectors[1]);
	dus->ios[0] += (__dus.ios[0] - ldus->ios[0]);
	dus->ios[1] += (__dus.ios[1] - ldus->ios[1]);
	dus->merges[0] += (__dus.merges[0] - ldus->merges[0]);
	dus->merges[1] += (__dus.merges[1] - ldus->merges[1]);
	dus->ticks[0] += (__dus.ticks[0] - ldus->ticks[0]);
	dus->ticks[1] += (__dus.ticks[1] - ldus->ticks[1]);
	dus->io_ticks += (__dus.io_ticks - ldus->io_ticks);
	dus->time_in_queue += (__dus.time_in_queue - ldus->time_in_queue);

	fio_gettime(&t, NULL);
	du->msec += mtime_since(&du->time, &t);
	memcpy(&du->time, &t, sizeof(t));
	memcpy(ldus, &__dus, sizeof(__dus));
	}

	void update_io_ticks(void)
	{
	struct flist_head *entry;
	struct disk_util *du;

	dprint(FD_DISKUTIL, "update io ticks\n");

	flist_for_each(entry, &disk_list) {
	du = flist_entry(entry, struct disk_util, list);
	update_io_tick_disk(du);
	}
	}

	static struct disk_util *disk_util_exists(int major, int minor)
	{
	struct flist_head *entry;
	struct disk_util *du;

	flist_for_each(entry, &disk_list) {
	du = flist_entry(entry, struct disk_util, list);

	if (major == du->major && minor == du->minor)
	return du;
	}

	return NULL;
	}

	static int get_device_numbers(char file_name, int maj, int *min)
	{
	struct stat st;
	int majdev, mindev;
	char tempname[PATH_MAX], *p;

	if (!lstat(file_name, &st)) {
	if (S_ISBLK(st.st_mode)) {
	majdev = major(st.st_rdev);
	mindev = minor(st.st_rdev);
	} else if (S_ISCHR(st.st_mode)) {
	majdev = major(st.st_rdev);
	mindev = minor(st.st_rdev);
	if (fio_lookup_raw(st.st_rdev, &majdev, &mindev))
	return -1;
	} else if (S_ISFIFO(st.st_mode))
	return -1;
	else {
	majdev = major(st.st_dev);
	mindev = minor(st.st_dev);
	}
	} else {
	/*
	* must be a file, open "." in that path
	*/
	strncpy(tempname, file_name, PATH_MAX - 1);
	p = dirname(tempname);
	if (stat(p, &st)) {
	perror("disk util stat");
	return -1;
	}

	majdev = major(st.st_dev);
	mindev = minor(st.st_dev);
	}

	*min = mindev;
	*maj = majdev;

	return 0;
	}

	static int read_block_dev_entry(char path, int maj, int *min)
	{
	char line[256], *p;
	FILE *f;

	f = fopen(path, "r");
	if (!f) {
	perror("open path");
	return 1;
	}

	p = fgets(line, sizeof(line), f);
	fclose(f);

	if (!p)
	return 1;

	if (sscanf(p, "%u:%u", maj, min) != 2)
	return 1;

	return 0;
	}

	static void find_add_disk_slaves(struct thread_data td, char path,
	struct disk_util *masterdu)
	{
	DIR *dirhandle = NULL;
	struct dirent *dirent = NULL;
	char slavesdir[PATH_MAX], temppath[PATH_MAX], slavepath[PATH_MAX];
	struct disk_util *slavedu = NULL;
	int majdev, mindev;
	ssize_t linklen;

	sprintf(slavesdir, "%s/%s", path, "slaves");
	dirhandle = opendir(slavesdir);
	if (!dirhandle)
	return;

	while ((dirent = readdir(dirhandle)) != NULL) {
	if (!strcmp(dirent->d_name, ".") \|\|
	!strcmp(dirent->d_name, ".."))
	continue;

	sprintf(temppath, "%s/%s", slavesdir, dirent->d_name);
	/* Can we always assume that the slaves device entries
	* are links to the real directories for the slave
	* devices?
	*/
	linklen = readlink(temppath, slavepath, PATH_MAX - 0);
	if (linklen < 0) {
	perror("readlink() for slave device.");
	return;
	}
	slavepath[linklen] = '\0';

	sprintf(temppath, "%s/%s/dev", slavesdir, slavepath);
	if (read_block_dev_entry(temppath, &majdev, &mindev)) {
	perror("Error getting slave device numbers.");
	return;
	}

	/*
	* See if this maj,min already exists
	*/
	slavedu = disk_util_exists(majdev, mindev);
	if (slavedu)
	continue;

	sprintf(temppath, "%s/%s", slavesdir, slavepath);
	__init_per_file_disk_util(td, majdev, mindev, temppath);
	slavedu = disk_util_exists(majdev, mindev);

	/* Should probably use an assert here. slavedu should
	* always be present at this point. */
	if (slavedu) {
	slavedu->users++;
	flist_add_tail(&slavedu->slavelist, &masterdu->slaves);
	}
	}

	closedir(dirhandle);
	}

	static struct disk_util disk_util_add(struct thread_data td, int majdev,
	int mindev, char *path)
	{
	struct disk_util du, __du;
	struct flist_head *entry;

	dprint(FD_DISKUTIL, "add maj/min %d/%d: %s\n", majdev, mindev, path);

	du = smalloc(sizeof(*du));
	memset(du, 0, sizeof(*du));
	INIT_FLIST_HEAD(&du->list);
	sprintf(du->path, "%s/stat", path);
	du->name = smalloc_strdup(basename(path));
	du->sysfs_root = path;
	du->major = majdev;
	du->minor = mindev;
	INIT_FLIST_HEAD(&du->slavelist);
	INIT_FLIST_HEAD(&du->slaves);
	du->lock = fio_mutex_init(1);
	du->users = 0;

	flist_for_each(entry, &disk_list) {
	__du = flist_entry(entry, struct disk_util, list);

	dprint(FD_DISKUTIL, "found %s in list\n", __du->name);

	if (!strcmp(du->name, __du->name)) {
	disk_util_free(du);
	return __du;
	}
	}

	dprint(FD_DISKUTIL, "add %s to list\n", du->name);

	fio_gettime(&du->time, NULL);
	get_io_ticks(du, &du->last_dus);

	flist_add_tail(&du->list, &disk_list);
	find_add_disk_slaves(td, path, du);
	return du;
	}

	static int check_dev_match(int majdev, int mindev, char *path)
	{
	int major, minor;

	if (read_block_dev_entry(path, &major, &minor))
	return 1;

	if (majdev == major && mindev == minor)
	return 0;

	return 1;
	}

	static int find_block_dir(int majdev, int mindev, char *path, int link_ok)
	{
	struct dirent *dir;
	struct stat st;
	int found = 0;
	DIR *D;

	D = opendir(path);
	if (!D)
	return 0;

	while ((dir = readdir(D)) != NULL) {
	char full_path[256];

	if (!strcmp(dir->d_name, ".") \|\| !strcmp(dir->d_name, ".."))
	continue;

	sprintf(full_path, "%s/%s", path, dir->d_name);

	if (!strcmp(dir->d_name, "dev")) {
	if (!check_dev_match(majdev, mindev, full_path)) {
	found = 1;
	break;
	}
	}

	if (link_ok) {
	if (stat(full_path, &st) == -1) {
	perror("stat");
	break;
	}
	} else {
	if (lstat(full_path, &st) == -1) {
	perror("stat");
	break;
	}
	}

	if (!S_ISDIR(st.st_mode) \|\| S_ISLNK(st.st_mode))
	continue;

	found = find_block_dir(majdev, mindev, full_path, 0);
	if (found) {
	strcpy(path, full_path);
	break;
	}
	}

	closedir(D);
	return found;
	}

	static struct disk_util __init_per_file_disk_util(struct thread_data td,
	int majdev, int mindev,
	char *path)
	{
	struct stat st;
	char tmp[PATH_MAX];
	char *p;

	/*
	* If there's a ../queue/ directory there, we are inside a partition.
	* Check if that is the case and jump back. For loop/md/dm etc we
	* are already in the right spot.
	*/
	sprintf(tmp, "%s/../queue", path);
	if (!stat(tmp, &st)) {
	p = dirname(path);
	sprintf(tmp, "%s/queue", p);
	if (stat(tmp, &st)) {
	log_err("unknown sysfs layout\n");
	return NULL;
	}
	strncpy(tmp, p, PATH_MAX - 1);
	sprintf(path, "%s", tmp);
	}

	if (td->o.ioscheduler && !td->sysfs_root)
	td->sysfs_root = strdup(path);

	return disk_util_add(td, majdev, mindev, path);
	}

	static struct disk_util init_per_file_disk_util(struct thread_data td,
	char *filename)
	{

	char foo[PATH_MAX];
	struct disk_util *du;
	int mindev, majdev;

	if (get_device_numbers(filename, &majdev, &mindev))
	return NULL;

	dprint(FD_DISKUTIL, "%s belongs to maj/min %d/%d\n", filename, majdev,
	mindev);

	du = disk_util_exists(majdev, mindev);
	if (du) {
	if (td->o.ioscheduler && !td->sysfs_root)
	td->sysfs_root = strdup(du->sysfs_root);

	return du;
	}

	/*
	* for an fs without a device, we will repeatedly stat through
	* sysfs which can take oodles of time for thousands of files. so
	* cache the last lookup and compare with that before going through
	* everything again.
	*/
	if (mindev == last_mindev && majdev == last_majdev)
	return last_du;

	last_mindev = mindev;
	last_majdev = majdev;

	sprintf(foo, "/sys/block");
	if (!find_block_dir(majdev, mindev, foo, 1))
	return NULL;

	return __init_per_file_disk_util(td, majdev, mindev, foo);
	}

	static struct disk_util __init_disk_util(struct thread_data td,
	struct fio_file *f)
	{
	return init_per_file_disk_util(td, f->file_name);
	}

	void init_disk_util(struct thread_data *td)
	{
	struct fio_file *f;
	unsigned int i;

	if (!td->o.do_disk_util \|\|
	(td->io_ops->flags & (FIO_DISKLESSIO \| FIO_NODISKUTIL)))
	return;

	for_each_file(td, f, i)
	f->du = __init_disk_util(td, f);
	}

	static void aggregate_slaves_stats(struct disk_util *masterdu)
	{
	struct disk_util_stat *dus;
	struct flist_head *entry;
	struct disk_util *slavedu;
	double util, max_util = 0;
	int slavecount = 0;

	unsigned merges[2] = { 0, };
	unsigned ticks[2] = { 0, };
	unsigned time_in_queue = { 0, };
	unsigned long long sectors[2] = { 0, };
	unsigned ios[2] = { 0, };

	flist_for_each(entry, &masterdu->slaves) {
	slavedu = flist_entry(entry, struct disk_util, slavelist);
	dus = &slavedu->dus;
	ios[0] += dus->ios[0];
	ios[1] += dus->ios[1];
	merges[0] += dus->merges[0];
	merges[1] += dus->merges[1];
	sectors[0] += dus->sectors[0];
	sectors[1] += dus->sectors[1];
	ticks[0] += dus->ticks[0];
	ticks[1] += dus->ticks[1];
	time_in_queue += dus->time_in_queue;
	++slavecount;

	util = (double) (100 * dus->io_ticks / (double) slavedu->msec);
	/* System utilization is the utilization of the
	* component with the highest utilization.
	*/
	if (util > max_util)
	max_util = util;

	}

	if (max_util > 100.0)
	max_util = 100.0;

	log_info(", aggrios=%u/%u, aggrmerge=%u/%u, aggrticks=%u/%u,"
	" aggrin_queue=%u, aggrutil=%3.2f%%",
	ios[0]/slavecount, ios[1]/slavecount,
	merges[0]/slavecount, merges[1]/slavecount,
	ticks[0]/slavecount, ticks[1]/slavecount,
	time_in_queue/slavecount, max_util);

	}

	void show_disk_util(void)
	{
	struct disk_util_stat *dus;
	struct flist_head entry, next;
	struct disk_util *du;
	double util;

	if (flist_empty(&disk_list))
	return;

	log_info("\nDisk stats (read/write):\n");

	flist_for_each(entry, &disk_list) {
	du = flist_entry(entry, struct disk_util, list);
	dus = &du->dus;

	util = (double) 100 * du->dus.io_ticks / (double) du->msec;
	if (util > 100.0)
	util = 100.0;

	/* If this node is the slave of a master device, as
	* happens in case of software RAIDs, inward-indent
	* this stats line to reflect a master-slave
	* relationship. Because the master device gets added
	* before the slave devices, we can safely assume that
	* the master's stats line has been displayed in a
	* previous iteration of this loop.
	*/
	if (!flist_empty(&du->slavelist))
	log_info(" ");

	log_info(" %s: ios=%u/%u, merge=%u/%u, ticks=%u/%u, "
	"in_queue=%u, util=%3.2f%%", du->name,
	dus->ios[0], dus->ios[1],
	dus->merges[0], dus->merges[1],
	dus->ticks[0], dus->ticks[1],
	dus->time_in_queue, util);

	/* If the device has slaves, aggregate the stats for
	* those slave devices also.
	*/
	if (!flist_empty(&du->slaves))
	aggregate_slaves_stats(du);

	log_info("\n");
	}

	/*
	* now free the list
	*/
	flist_for_each_safe(entry, next, &disk_list) {
	flist_del(entry);
	du = flist_entry(entry, struct disk_util, list);
	disk_util_free(du);
	}
	}