X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=diskutil.c;h=9767ea255c882a66511954472a2a9f70f56c5d41;hp=9fb31bf2be44f6c6e9f997e204a10fb6b7574aa1;hb=5ccdfd74e2e13c61eec307e53a50f3f73f0afe7a;hpb=ac0be2acff3864979e5e260d332d25ca90e22417

diff --git a/diskutil.c b/diskutil.c
index 9fb31bf2..9767ea25 100644
--- a/diskutil.c
+++ b/diskutil.c
@@ -6,16 +6,43 @@
 #include <dirent.h>
 #include <libgen.h>
 #include <math.h>
+#include <assert.h>
 
 #include "fio.h"
+#include "smalloc.h"
+#include "diskutil.h"
+#include "helper_thread.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 fio_mutex *disk_util_mutex;
+
+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_first_entry(&du->slaves, struct disk_util, slavelist);
+		flist_del(&slave->slavelist);
+		slave->users--;
+	}
+
+	fio_mutex_remove(du->lock);
+	free(du->sysfs_root);
+	sfree(du);
+}
 
 static int get_io_ticks(struct disk_util *du, struct disk_util_stat *dus)
 {
 	unsigned in_flight;
+	unsigned long long sectors[2];
 	char line[256];
 	FILE *f;
 	char *p;
@@ -35,14 +62,22 @@ static int get_io_ticks(struct disk_util *du, struct disk_util_stat *dus)
 
 	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);
+	ret = sscanf(p, "%llu %llu %llu %llu %llu %llu %llu %llu %u %llu %llu\n",
+				(unsigned long long *) &dus->s.ios[0],
+				(unsigned long long *) &dus->s.merges[0],
+				&sectors[0],
+				(unsigned long long *) &dus->s.ticks[0],
+				(unsigned long long *) &dus->s.ios[1],
+				(unsigned long long *) &dus->s.merges[1],
+				&sectors[1],
+				(unsigned long long *) &dus->s.ticks[1],
+				&in_flight,
+				(unsigned long long *) &dus->s.io_ticks,
+				(unsigned long long *) &dus->s.time_in_queue);
 	fclose(f);
 	dprint(FD_DISKUTIL, "%s: stat read ok? %d\n", du->path, ret == 1);
+	dus->s.sectors[0] = sectors[0];
+	dus->s.sectors[1] = sectors[1];
 	return ret != 11;
 }
 
@@ -51,40 +86,51 @@ 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);
+	dus->s.sectors[0] += (__dus.s.sectors[0] - ldus->s.sectors[0]);
+	dus->s.sectors[1] += (__dus.s.sectors[1] - ldus->s.sectors[1]);
+	dus->s.ios[0] += (__dus.s.ios[0] - ldus->s.ios[0]);
+	dus->s.ios[1] += (__dus.s.ios[1] - ldus->s.ios[1]);
+	dus->s.merges[0] += (__dus.s.merges[0] - ldus->s.merges[0]);
+	dus->s.merges[1] += (__dus.s.merges[1] - ldus->s.merges[1]);
+	dus->s.ticks[0] += (__dus.s.ticks[0] - ldus->s.ticks[0]);
+	dus->s.ticks[1] += (__dus.s.ticks[1] - ldus->s.ticks[1]);
+	dus->s.io_ticks += (__dus.s.io_ticks - ldus->s.io_ticks);
+	dus->s.time_in_queue += (__dus.s.time_in_queue - ldus->s.time_in_queue);
 
 	fio_gettime(&t, NULL);
-	du->msec += mtime_since(&du->time, &t);
+	dus->s.msec += mtime_since(&du->time, &t);
 	memcpy(&du->time, &t, sizeof(t));
-	memcpy(ldus, &__dus, sizeof(__dus));
+	memcpy(&ldus->s, &__dus.s, sizeof(__dus.s));
 }
 
-void update_io_ticks(void)
+int update_io_ticks(void)
 {
 	struct flist_head *entry;
 	struct disk_util *du;
+	int ret = 0;
 
 	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);
-	}
+	fio_mutex_down(disk_util_mutex);
+
+	if (!helper_should_exit()) {
+		flist_for_each(entry, &disk_list) {
+			du = flist_entry(entry, struct disk_util, list);
+			update_io_tick_disk(du);
+		}
+	} else
+		ret = 1;
+
+	fio_mutex_up(disk_util_mutex);
+	return ret;
 }
 
 static struct disk_util *disk_util_exists(int major, int minor)
@@ -92,81 +138,216 @@ static struct disk_util *disk_util_exists(int major, int minor)
 	struct flist_head *entry;
 	struct disk_util *du;
 
+	fio_mutex_down(disk_util_mutex);
+
 	flist_for_each(entry, &disk_list) {
 		du = flist_entry(entry, struct disk_util, list);
 
-		if (major == du->major && minor == du->minor)
+		if (major == du->major && minor == du->minor) {
+			fio_mutex_up(disk_util_mutex);
 			return du;
+		}
 	}
 
+	fio_mutex_up(disk_util_mutex);
 	return NULL;
 }
 
-static void disk_util_add(int majdev, int mindev, char *path)
+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
+		 */
+		tempname[PATH_MAX - 1] = '\0';
+		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 - 1);
+		if (linklen  < 0) {
+			perror("readlink() for slave device.");
+			closedir(dirhandle);
+			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.");
+			closedir(dirhandle);
+			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;
+	int l;
 
 	dprint(FD_DISKUTIL, "add maj/min %d/%d: %s\n", majdev, mindev, path);
 
-	du = malloc(sizeof(*du));
+	du = smalloc(sizeof(*du));
+	if (!du)
+		return NULL;
+
 	memset(du, 0, sizeof(*du));
 	INIT_FLIST_HEAD(&du->list);
-	sprintf(du->path, "%s/stat", path);
-	du->name = strdup(basename(path));
-	du->sysfs_root = path;
+	l = snprintf(du->path, sizeof(du->path), "%s/stat", path);
+	if (l < 0 || l >= sizeof(du->path)) {
+		log_err("constructed path \"%.100s[...]/stat\" larger than buffer (%zu bytes)\n",
+			path, sizeof(du->path) - 1);
+		sfree(du);
+		return NULL;
+	}
+	strncpy((char *) du->dus.name, basename(path), FIO_DU_NAME_SZ - 1);
+	du->sysfs_root = strdup(path);
 	du->major = majdev;
 	du->minor = mindev;
+	INIT_FLIST_HEAD(&du->slavelist);
+	INIT_FLIST_HEAD(&du->slaves);
+	du->lock = fio_mutex_init(FIO_MUTEX_UNLOCKED);
+	du->users = 0;
+
+	fio_mutex_down(disk_util_mutex);
 
 	flist_for_each(entry, &disk_list) {
 		__du = flist_entry(entry, struct disk_util, list);
 
-		dprint(FD_DISKUTIL, "found %s in list\n", __du->name);
+		dprint(FD_DISKUTIL, "found %s in list\n", __du->dus.name);
 
-		if (!strcmp(du->name, __du->name)) {
-			free(du->name);
-			free(du);
-			return;
+		if (!strcmp((char *) du->dus.name, (char *) __du->dus.name)) {
+			disk_util_free(du);
+			fio_mutex_up(disk_util_mutex);
+			return __du;
 		}
 	}
 
-	dprint(FD_DISKUTIL, "add %s to list\n", du->name);
+	dprint(FD_DISKUTIL, "add %s to list\n", du->dus.name);
 
 	fio_gettime(&du->time, NULL);
 	get_io_ticks(du, &du->last_dus);
 
 	flist_add_tail(&du->list, &disk_list);
+	fio_mutex_up(disk_util_mutex);
+
+	find_add_disk_slaves(td, path, du);
+	return du;
 }
 
 static int check_dev_match(int majdev, int mindev, char *path)
 {
 	int major, minor;
-	char line[256], *p;
-	FILE *f;
 
-	f = fopen(path, "r");
-	if (!f) {
-		perror("open path");
+	if (read_block_dev_entry(path, &major, &minor))
 		return 1;
-	}
-
-	p = fgets(line, sizeof(line), f);
-	if (!p) {
-		fclose(f);
-		return 1;
-	}
 
-	if (sscanf(p, "%u:%u", &major, &minor) != 2) {
-		fclose(f);
-		return 1;
-	}
-
-	if (majdev == major && mindev == minor) {
-		fclose(f);
+	if (majdev == major && mindev == minor)
 		return 0;
-	}
 
-	fclose(f);
 	return 1;
 }
 
@@ -182,7 +363,7 @@ static int find_block_dir(int majdev, int mindev, char *path, int link_ok)
 		return 0;
 
 	while ((dir = readdir(D)) != NULL) {
-		char full_path[256];
+		char full_path[257];
 
 		if (!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, ".."))
 			continue;
@@ -222,54 +403,52 @@ static int find_block_dir(int majdev, int mindev, char *path, int link_ok)
 	return found;
 }
 
-static void __init_disk_util(struct thread_data *td, struct fio_file *f)
+static struct disk_util *__init_per_file_disk_util(struct thread_data *td,
+						   int majdev, int mindev,
+						   char *path)
 {
 	struct stat st;
-	char foo[PATH_MAX], tmp[PATH_MAX];
-	struct disk_util *du;
-	int mindev, majdev;
+	char tmp[PATH_MAX];
 	char *p;
 
-	if (!lstat(f->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;
-		} else if (S_ISFIFO(st.st_mode))
-			return;
-		else {
-			majdev = major(st.st_dev);
-			mindev = minor(st.st_dev);
-		}
-	} else {
-		/*
-		 * must be a file, open "." in that path
-		 */
-		strncpy(foo, f->file_name, PATH_MAX - 1);
-		p = dirname(foo);
-		if (stat(p, &st)) {
-			perror("disk util stat");
-			return;
+	/*
+	 * 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;
 		}
-
-		majdev = major(st.st_dev);
-		mindev = minor(st.st_dev);
+		tmp[PATH_MAX - 1] = '\0';
+		strncpy(tmp, p, PATH_MAX - 1);
+		sprintf(path, "%s", tmp);
 	}
 
-	dprint(FD_DISKUTIL, "%s belongs to maj/min %d/%d\n", f->file_name,
-							majdev, mindev);
+	return disk_util_add(td, majdev, mindev, path);
+}
 
-	du = disk_util_exists(majdev, mindev);
-	if (du) {
-		if (td->o.ioscheduler && !td->sysfs_root)
-			td->sysfs_root = strdup(du->sysfs_root);
+static struct disk_util *init_per_file_disk_util(struct thread_data *td,
+						 char *filename)
+{
 
-		return;
-	}
+	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)
+		return du;
 
 	/*
 	 * for an fs without a device, we will repeatedly stat through
@@ -278,36 +457,22 @@ static void __init_disk_util(struct thread_data *td, struct fio_file *f)
 	 * everything again.
 	 */
 	if (mindev == last_mindev && majdev == last_majdev)
-		return;
+		return last_du;
 
 	last_mindev = mindev;
 	last_majdev = majdev;
 
 	sprintf(foo, "/sys/block");
 	if (!find_block_dir(majdev, mindev, foo, 1))
-		return;
-
-	/*
-	 * 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", foo);
-	if (!stat(tmp, &st)) {
-		p = dirname(foo);
-		sprintf(tmp, "%s/queue", p);
-		if (stat(tmp, &st)) {
-			log_err("unknown sysfs layout\n");
-			return;
-		}
-		strncpy(tmp, p, PATH_MAX - 1);
-		sprintf(foo, "%s", tmp);
-	}
+		return NULL;
 
-	if (td->o.ioscheduler && !td->sysfs_root)
-		td->sysfs_root = strdup(foo);
+	return __init_per_file_disk_util(td, majdev, mindev, foo);
+}
 
-	disk_util_add(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)
@@ -316,48 +481,248 @@ void init_disk_util(struct thread_data *td)
 	unsigned int i;
 
 	if (!td->o.do_disk_util ||
-	    (td->io_ops->flags & (FIO_DISKLESSIO | FIO_NODISKUTIL)))
+	    td_ioengine_flagged(td, FIO_DISKLESSIO | FIO_NODISKUTIL))
 		return;
 
 	for_each_file(td, f, i)
-		__init_disk_util(td, f);
+		f->du = __init_disk_util(td, f);
 }
 
-void show_disk_util(void)
+static void show_agg_stats(struct disk_util_agg *agg, int terse,
+			   struct buf_output *out)
 {
+	if (!agg->slavecount)
+		return;
+
+	if (!terse) {
+		log_buf(out, ", aggrios=%llu/%llu, aggrmerge=%llu/%llu, "
+			 "aggrticks=%llu/%llu, aggrin_queue=%llu, "
+			 "aggrutil=%3.2f%%",
+			(unsigned long long) agg->ios[0] / agg->slavecount,
+			(unsigned long long) agg->ios[1] / agg->slavecount,
+			(unsigned long long) agg->merges[0] / agg->slavecount,
+			(unsigned long long) agg->merges[1] / agg->slavecount,
+			(unsigned long long) agg->ticks[0] / agg->slavecount,
+			(unsigned long long) agg->ticks[1] / agg->slavecount,
+			(unsigned long long) agg->time_in_queue / agg->slavecount,
+			agg->max_util.u.f);
+	} else {
+		log_buf(out, ";slaves;%llu;%llu;%llu;%llu;%llu;%llu;%llu;%3.2f%%",
+			(unsigned long long) agg->ios[0] / agg->slavecount,
+			(unsigned long long) agg->ios[1] / agg->slavecount,
+			(unsigned long long) agg->merges[0] / agg->slavecount,
+			(unsigned long long) agg->merges[1] / agg->slavecount,
+			(unsigned long long) agg->ticks[0] / agg->slavecount,
+			(unsigned long long) agg->ticks[1] / agg->slavecount,
+			(unsigned long long) agg->time_in_queue / agg->slavecount,
+			agg->max_util.u.f);
+	}
+}
+
+static void aggregate_slaves_stats(struct disk_util *masterdu)
+{
+	struct disk_util_agg *agg = &masterdu->agg;
 	struct disk_util_stat *dus;
-	struct flist_head *entry, *next;
-	struct disk_util *du;
+	struct flist_head *entry;
+	struct disk_util *slavedu;
 	double util;
 
-	if (flist_empty(&disk_list))
-		return;
+	flist_for_each(entry, &masterdu->slaves) {
+		slavedu = flist_entry(entry, struct disk_util, slavelist);
+		dus = &slavedu->dus;
+		agg->ios[0] += dus->s.ios[0];
+		agg->ios[1] += dus->s.ios[1];
+		agg->merges[0] += dus->s.merges[0];
+		agg->merges[1] += dus->s.merges[1];
+		agg->sectors[0] += dus->s.sectors[0];
+		agg->sectors[1] += dus->s.sectors[1];
+		agg->ticks[0] += dus->s.ticks[0];
+		agg->ticks[1] += dus->s.ticks[1];
+		agg->time_in_queue += dus->s.time_in_queue;
+		agg->slavecount++;
+
+		util = (double) (100 * dus->s.io_ticks / (double) slavedu->dus.s.msec);
+		/* System utilization is the utilization of the
+		 * component with the highest utilization.
+		 */
+		if (util > agg->max_util.u.f)
+			agg->max_util.u.f = util;
 
-	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;
-
-		log_info("  %s: ios=%u/%u, merge=%u/%u, ticks=%u/%u, "
-			 "in_queue=%u, util=%3.2f%%\n", 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 (agg->max_util.u.f > 100.0)
+		agg->max_util.u.f = 100.0;
+}
+
+void disk_util_prune_entries(void)
+{
+	fio_mutex_down(disk_util_mutex);
+
+	while (!flist_empty(&disk_list)) {
+		struct disk_util *du;
+
+		du = flist_first_entry(&disk_list, struct disk_util, list);
+		flist_del(&du->list);
+		disk_util_free(du);
+	}
+
+	last_majdev = last_mindev = -1;
+	fio_mutex_up(disk_util_mutex);
+	fio_mutex_remove(disk_util_mutex);
+}
+
+void print_disk_util(struct disk_util_stat *dus, struct disk_util_agg *agg,
+		     int terse, struct buf_output *out)
+{
+	double util = 0;
+
+	if (dus->s.msec)
+		util = (double) 100 * dus->s.io_ticks / (double) dus->s.msec;
+	if (util > 100.0)
+		util = 100.0;
+
+	if (!terse) {
+		if (agg->slavecount)
+			log_buf(out, "  ");
+
+		log_buf(out, "  %s: ios=%llu/%llu, merge=%llu/%llu, "
+			 "ticks=%llu/%llu, in_queue=%llu, util=%3.2f%%",
+				dus->name,
+				(unsigned long long) dus->s.ios[0],
+				(unsigned long long) dus->s.ios[1],
+				(unsigned long long) dus->s.merges[0],
+				(unsigned long long) dus->s.merges[1],
+				(unsigned long long) dus->s.ticks[0],
+				(unsigned long long) dus->s.ticks[1],
+				(unsigned long long) dus->s.time_in_queue,
+				util);
+	} else {
+		log_buf(out, ";%s;%llu;%llu;%llu;%llu;%llu;%llu;%llu;%3.2f%%",
+				dus->name,
+				(unsigned long long) dus->s.ios[0],
+				(unsigned long long) dus->s.ios[1],
+				(unsigned long long) dus->s.merges[0],
+				(unsigned long long) dus->s.merges[1],
+				(unsigned long long) dus->s.ticks[0],
+				(unsigned long long) dus->s.ticks[1],
+				(unsigned long long) dus->s.time_in_queue,
+				util);
 	}
 
 	/*
-	 * now free the list
+	 * If the device has slaves, aggregate the stats for
+	 * those slave devices also.
 	 */
-	flist_for_each_safe(entry, next, &disk_list) {
-		flist_del(entry);
+	show_agg_stats(agg, terse, out);
+
+	if (!terse)
+		log_buf(out, "\n");
+}
+
+void json_array_add_disk_util(struct disk_util_stat *dus,
+		struct disk_util_agg *agg, struct json_array *array)
+{
+	struct json_object *obj;
+	double util = 0;
+
+	if (dus->s.msec)
+		util = (double) 100 * dus->s.io_ticks / (double) dus->s.msec;
+	if (util > 100.0)
+		util = 100.0;
+
+	obj = json_create_object();
+	json_array_add_value_object(array, obj);
+
+	json_object_add_value_string(obj, "name", dus->name);
+	json_object_add_value_int(obj, "read_ios", dus->s.ios[0]);
+	json_object_add_value_int(obj, "write_ios", dus->s.ios[1]);
+	json_object_add_value_int(obj, "read_merges", dus->s.merges[0]);
+	json_object_add_value_int(obj, "write_merges", dus->s.merges[1]);
+	json_object_add_value_int(obj, "read_ticks", dus->s.ticks[0]);
+	json_object_add_value_int(obj, "write_ticks", dus->s.ticks[1]);
+	json_object_add_value_int(obj, "in_queue", dus->s.time_in_queue);
+	json_object_add_value_float(obj, "util", util);
+
+	/*
+	 * If the device has slaves, aggregate the stats for
+	 * those slave devices also.
+	 */
+	if (!agg->slavecount)
+		return;
+	json_object_add_value_int(obj, "aggr_read_ios",
+				agg->ios[0] / agg->slavecount);
+	json_object_add_value_int(obj, "aggr_write_ios",
+				agg->ios[1] / agg->slavecount);
+	json_object_add_value_int(obj, "aggr_read_merges",
+				agg->merges[0] / agg->slavecount);
+	json_object_add_value_int(obj, "aggr_write_merge",
+				agg->merges[1] / agg->slavecount);
+	json_object_add_value_int(obj, "aggr_read_ticks",
+				agg->ticks[0] / agg->slavecount);
+	json_object_add_value_int(obj, "aggr_write_ticks",
+				agg->ticks[1] / agg->slavecount);
+	json_object_add_value_int(obj, "aggr_in_queue",
+				agg->time_in_queue / agg->slavecount);
+	json_object_add_value_float(obj, "aggr_util", agg->max_util.u.f);
+}
+
+static void json_object_add_disk_utils(struct json_object *obj,
+				       struct flist_head *head)
+{
+	struct json_array *array = json_create_array();
+	struct flist_head *entry;
+	struct disk_util *du;
+
+	json_object_add_value_array(obj, "disk_util", array);
+
+	flist_for_each(entry, head) {
 		du = flist_entry(entry, struct disk_util, list);
-		free(du->name);
-		free(du);
+
+		aggregate_slaves_stats(du);
+		json_array_add_disk_util(&du->dus, &du->agg, array);
 	}
 }
+
+void show_disk_util(int terse, struct json_object *parent,
+		    struct buf_output *out)
+{
+	struct flist_head *entry;
+	struct disk_util *du;
+	bool do_json;
+
+	if (!disk_util_mutex)
+		return;
+
+	fio_mutex_down(disk_util_mutex);
+
+	if (flist_empty(&disk_list)) {
+		fio_mutex_up(disk_util_mutex);
+		return;
+	}
+
+	if ((output_format & FIO_OUTPUT_JSON) && parent)
+		do_json = true;
+	else
+		do_json = false;
+
+	if (!terse && !do_json)
+		log_buf(out, "\nDisk stats (read/write):\n");
+
+	if (do_json)
+		json_object_add_disk_utils(parent, &disk_list);
+	else if (output_format & ~(FIO_OUTPUT_JSON | FIO_OUTPUT_JSON_PLUS)) {
+		flist_for_each(entry, &disk_list) {
+			du = flist_entry(entry, struct disk_util, list);
+
+			aggregate_slaves_stats(du);
+			print_disk_util(&du->dus, &du->agg, terse, out);
+		}
+	}
+
+	fio_mutex_up(disk_util_mutex);
+}
+
+void setup_disk_util(void)
+{
+	disk_util_mutex = fio_mutex_init(FIO_MUTEX_UNLOCKED);
+}