[fio.git] / steadystate.c

#include <stdlib.h>

#include "fio.h"
#include "steadystate.h"
#include "helper_thread.h"

bool steadystate_enabled = false;

static void steadystate_alloc(struct thread_data *td)
{
	int i;

	td->ss.bw_data = malloc(td->ss.dur * sizeof(unsigned long));
	td->ss.iops_data = malloc(td->ss.dur * sizeof(unsigned long));
	/* initialize so that it is obvious if the cache is not full in the output */
	for (i = 0; i < td->ss.dur; i++)
		td->ss.iops_data[i] = td->ss.bw_data[i] = 0;
}

void steadystate_setup(void)
{
	int i, prev_groupid;
	struct thread_data *td, *prev_td;

	if (!steadystate_enabled)
		return;

	/*
	 * if group reporting is enabled, identify the last td
	 * for each group and use it for storing steady state
	 * data
	 */
	prev_groupid = -1;
	prev_td = NULL;
	for_each_td(td, i) {
		if (td->ts.ss == NULL)
			continue;

		if (!td->o.group_reporting) {
			steadystate_alloc(td);
			td->ss.state |= __FIO_SS_DATA;
			continue;
		}

		if (prev_groupid != td->groupid) {
			if (prev_td != NULL) {
				prev_td->ss.state |= __FIO_SS_DATA;
				steadystate_alloc(prev_td);
			}
			prev_groupid = td->groupid;
		}
		prev_td = td;
	}

	if (prev_td != NULL && prev_td->o.group_reporting) {
		prev_td->ss.state |= __FIO_SS_DATA;
		steadystate_alloc(prev_td);
	}
}

static bool steadystate_slope(unsigned long iops, unsigned long bw,
			      struct thread_data *td)
{
	int i, j;
	double result;
	struct steadystate_data *ss = &td->ss;
	unsigned long new_val;

	ss->bw_data[ss->tail] = bw;
	ss->iops_data[ss->tail] = iops;

	if (ss->state & __FIO_SS_IOPS)
		new_val = iops;
	else
		new_val = bw;

	if (ss->tail < ss->head || (ss->tail - ss->head == ss->dur - 1)) {
		if (ss->sum_y == 0) {	/* first time through */
			for(i = 0; i < ss->dur; i++) {
				if (ss->state & __FIO_SS_IOPS)
					ss->sum_y += ss->iops_data[i];
				else
					ss->sum_y += ss->bw_data[i];
				j = ss->head + i;
				if (j >= ss->dur)
					j -= ss->dur;
				if (ss->state & __FIO_SS_IOPS)
					ss->sum_xy += i * ss->iops_data[j];
				else
					ss->sum_xy += i * ss->bw_data[j];
			}
		} else {		/* easy to update the sums */
			ss->sum_y -= ss->oldest_y;
			ss->sum_y += new_val;
			ss->sum_xy = ss->sum_xy - ss->sum_y + ss->dur * new_val;
		}

		if (ss->state & __FIO_SS_IOPS)
			ss->oldest_y = ss->iops_data[ss->head];
		else
			ss->oldest_y = ss->bw_data[ss->head];

		/*
		 * calculate slope as (sum_xy - sum_x * sum_y / n) / (sum_(x^2)
		 * - (sum_x)^2 / n) This code assumes that all x values are
		 * equally spaced when they are often off by a few milliseconds.
		 * This assumption greatly simplifies the calculations.
		 */
		ss->slope = (ss->sum_xy - (double) ss->sum_x * ss->sum_y / ss->dur) /
				(ss->sum_x_sq - (double) ss->sum_x * ss->sum_x / ss->dur);
		if (ss->state & __FIO_SS_PCT)
			ss->criterion = 100.0 * ss->slope / (ss->sum_y / ss->dur);
		else
			ss->criterion = ss->slope;

		dprint(FD_STEADYSTATE, "sum_y: %llu, sum_xy: %llu, slope: %f, "
					"criterion: %f, limit: %f\n",
					ss->sum_y, ss->sum_xy, ss->slope,
					ss->criterion, ss->limit);

		result = ss->criterion * (ss->criterion < 0.0 ? -1.0 : 1.0);
		if (result < ss->limit)
			return true;
	}

	ss->tail = (ss->tail + 1) % ss->dur;
	if (ss->tail <= ss->head)
		ss->head = (ss->head + 1) % ss->dur;

	return false;
}

static bool steadystate_deviation(unsigned long iops, unsigned long bw,
				  struct thread_data *td)
{
	int i;
	double diff;
	double mean;

	struct steadystate_data *ss = &td->ss;

	ss->bw_data[ss->tail] = bw;
	ss->iops_data[ss->tail] = iops;

	if (ss->tail < ss->head || (ss->tail - ss->head == ss->dur - 1)) {
		if (ss->sum_y == 0) {	/* first time through */
			for(i = 0; i < ss->dur; i++)
				if (ss->state & __FIO_SS_IOPS)
					ss->sum_y += ss->iops_data[i];
				else
					ss->sum_y += ss->bw_data[i];
		} else {		/* easy to update the sum */
			ss->sum_y -= ss->oldest_y;
			if (ss->state & __FIO_SS_IOPS)
				ss->sum_y += ss->iops_data[ss->tail];
			else
				ss->sum_y += ss->bw_data[ss->tail];
		}

		if (ss->state & __FIO_SS_IOPS)
			ss->oldest_y = ss->iops_data[ss->head];
		else
			ss->oldest_y = ss->bw_data[ss->head];

		mean = (double) ss->sum_y / ss->dur;
		ss->deviation = 0.0;

		for (i = 0; i < ss->dur; i++) {
			if (ss->state & __FIO_SS_IOPS)
				diff = ss->iops_data[i] - mean;
			else
				diff = ss->bw_data[i] - mean;
			ss->deviation = max(ss->deviation, diff * (diff < 0.0 ? -1.0 : 1.0));
		}

		if (ss->state & __FIO_SS_PCT)
			ss->criterion = 100.0 * ss->deviation / mean;
		else
			ss->criterion = ss->deviation;

		dprint(FD_STEADYSTATE, "sum_y: %llu, mean: %f, max diff: %f, "
					"objective: %f, limit: %f\n",
					ss->sum_y, mean, ss->deviation,
					ss->criterion, ss->limit);

		if (ss->criterion < ss->limit)
			return true;
	}

	ss->tail = (ss->tail + 1) % ss->dur;
	if (ss->tail <= ss->head)
		ss->head = (ss->head + 1) % ss->dur;

	return false;
}

void steadystate_check(void)
{
	int i, j, ddir, prev_groupid, group_ramp_time_over = 0;
	unsigned long rate_time;
	struct thread_data *td, *td2;
	struct timeval now;
	unsigned long group_bw = 0, group_iops = 0;
	unsigned long long td_iops;
	unsigned long long td_bytes;
	bool ret;

	prev_groupid = -1;
	for_each_td(td, i) {
		struct steadystate_data *ss = &td->ss;

		if (!ss->dur || td->runstate <= TD_SETTING_UP ||
		    td->runstate >= TD_EXITED || (ss->state & __FIO_SS_ATTAINED))
			continue;

		td_iops = 0;
		td_bytes = 0;
		if (!td->o.group_reporting ||
		    (td->o.group_reporting && td->groupid != prev_groupid)) {
			group_bw = 0;
			group_iops = 0;
			group_ramp_time_over = 0;
		}
		prev_groupid = td->groupid;

		fio_gettime(&now, NULL);
		if (ss->ramp_time && !(ss->state & __FIO_SS_RAMP_OVER)) {
			/*
			 * Begin recording data one second after ss->ramp_time
			 * has elapsed
			 */
			if (utime_since(&td->epoch, &now) >= (ss->ramp_time + 1000000L))
				ss->state |= __FIO_SS_RAMP_OVER;
		}

		td_io_u_lock(td);
		for (ddir = DDIR_READ; ddir < DDIR_RWDIR_CNT; ddir++) {
			td_iops += td->io_blocks[ddir];
			td_bytes += td->io_bytes[ddir];
		}
		td_io_u_unlock(td);

		rate_time = mtime_since(&ss->prev_time, &now);
		memcpy(&ss->prev_time, &now, sizeof(now));

		/*
		 * Begin monitoring when job starts but don't actually use
		 * data in checking stopping criterion until ss->ramp_time is
		 * over. This ensures that we will have a sane value in
		 * prev_iops/bw the first time through after ss->ramp_time
		 * is done.
		 */
		if (ss->state & __FIO_SS_RAMP_OVER) {
			group_bw += 1000 * (td_bytes - ss->prev_bytes) / rate_time;
			group_iops += 1000 * (td_iops - ss->prev_iops) / rate_time;
			++group_ramp_time_over;
		}
		ss->prev_iops = td_iops;
		ss->prev_bytes = td_bytes;

		if (td->o.group_reporting && !(ss->state & __FIO_SS_DATA))
			continue;

		/*
		 * Don't begin checking criterion until ss->ramp_time is over
		 * for at least one thread in group
		 */
		if (!group_ramp_time_over)
			continue;

		dprint(FD_STEADYSTATE, "steadystate_check() thread: %d, "
					"groupid: %u, rate_msec: %ld, "
					"iops: %lu, bw: %lu, head: %d, tail: %d\n",
					i, td->groupid, rate_time, group_iops,
					group_bw, ss->head, ss->tail);

		if (td->o.ss & __FIO_SS_SLOPE)
			ret = steadystate_slope(group_iops, group_bw, td);
		else
			ret = steadystate_deviation(group_iops, group_bw, td);

		if (ret) {
			if (td->o.group_reporting) {
				for_each_td(td2, j) {
					if (td2->groupid == td->groupid) {
						td2->ss.state |= __FIO_SS_ATTAINED;
						fio_mark_td_terminate(td2);
					}
				}
			} else {
				ss->state |= __FIO_SS_ATTAINED;
				fio_mark_td_terminate(td);
			}
		}
	}
}

int td_steadystate_init(struct thread_data *td)
{
	struct steadystate_data *ss = &td->ss;
	struct thread_options *o = &td->o;
	struct thread_data *td2;
	int j;

	memset(ss, 0, sizeof(*ss));

	if (o->ss_dur) {
		steadystate_enabled = true;
		o->ss_dur /= 1000000L;

		/* put all steady state info in one place */
		ss->dur = o->ss_dur;
		ss->limit = o->ss_limit.u.f;
		ss->ramp_time = o->ss_ramp_time;

		ss->state = o->ss;
		if (!td->ss.ramp_time)
			ss->state |= __FIO_SS_RAMP_OVER;

		ss->sum_x = o->ss_dur * (o->ss_dur - 1) / 2;
		ss->sum_x_sq = (o->ss_dur - 1) * (o->ss_dur) * (2*o->ss_dur - 1) / 6;

		td->ts.ss = ss;
	}

	/* make sure that ss options are consistent within reporting group */
	for_each_td(td2, j) {
		if (td2->groupid == td->groupid) {
			struct steadystate_data *ss2 = &td2->ss;

			if (ss2->dur != ss->dur ||
			    ss2->limit != ss->limit ||
			    ss2->ramp_time != ss->ramp_time ||
			    ss2->state != ss->state ||
			    ss2->sum_x != ss->sum_x ||
			    ss2->sum_x_sq != ss->sum_x_sq) {
				td_verror(td, EINVAL, "job rejected: steadystate options must be consistent within reporting groups");
				return 1;
			}
		}
	}

	return 0;
}

unsigned long long steadystate_bw_mean(struct steadystate_data *ss)
{
	int i;
	unsigned long long sum;

	for (i = 0, sum = 0; i < ss->dur; i++)
		sum += ss->bw_data[i];

	return sum / ss->dur;
}

unsigned long long steadystate_iops_mean(struct steadystate_data *ss)
{
	int i;
	unsigned long long sum;

	for (i = 0, sum = 0; i < ss->dur; i++)
		sum += ss->iops_data[i];

	return sum / ss->dur;
}
Commit	Line	Data
	1	#include <stdlib.h>
	2
	3	#include "fio.h"
	4	#include "steadystate.h"
	5	#include "helper_thread.h"
	6
	7	bool steadystate_enabled = false;
	8
	9	static void steadystate_alloc(struct thread_data *td)
	10	{
	11	int i;
	12
	13	td->ss.bw_data = malloc(td->ss.dur * sizeof(unsigned long));
	14	td->ss.iops_data = malloc(td->ss.dur * sizeof(unsigned long));
	15	/* initialize so that it is obvious if the cache is not full in the output */
	16	for (i = 0; i < td->ss.dur; i++)
	17	td->ss.iops_data[i] = td->ss.bw_data[i] = 0;
	18	}
	19
	20	void steadystate_setup(void)
	21	{
	22	int i, prev_groupid;
	23	struct thread_data td, prev_td;
	24
	25	if (!steadystate_enabled)
	26	return;
	27
	28	/*
	29	* if group reporting is enabled, identify the last td
	30	* for each group and use it for storing steady state
	31	* data
	32	*/
	33	prev_groupid = -1;
	34	prev_td = NULL;
	35	for_each_td(td, i) {
	36	if (td->ts.ss == NULL)
	37	continue;
	38
	39	if (!td->o.group_reporting) {
	40	steadystate_alloc(td);
	41	td->ss.state \|= __FIO_SS_DATA;
	42	continue;
	43	}
	44
	45	if (prev_groupid != td->groupid) {
	46	if (prev_td != NULL) {
	47	prev_td->ss.state \|= __FIO_SS_DATA;
	48	steadystate_alloc(prev_td);
	49	}
	50	prev_groupid = td->groupid;
	51	}
	52	prev_td = td;
	53	}
	54
	55	if (prev_td != NULL && prev_td->o.group_reporting) {
	56	prev_td->ss.state \|= __FIO_SS_DATA;
	57	steadystate_alloc(prev_td);
	58	}
	59	}
	60
	61	static bool steadystate_slope(unsigned long iops, unsigned long bw,
	62	struct thread_data *td)
	63	{
	64	int i, j;
	65	double result;
	66	struct steadystate_data *ss = &td->ss;
	67	unsigned long new_val;
	68
	69	ss->bw_data[ss->tail] = bw;
	70	ss->iops_data[ss->tail] = iops;
	71
	72	if (ss->state & __FIO_SS_IOPS)
	73	new_val = iops;
	74	else
	75	new_val = bw;
	76
	77	if (ss->tail < ss->head \|\| (ss->tail - ss->head == ss->dur - 1)) {
	78	if (ss->sum_y == 0) { /* first time through */
	79	for(i = 0; i < ss->dur; i++) {
	80	if (ss->state & __FIO_SS_IOPS)
	81	ss->sum_y += ss->iops_data[i];
	82	else
	83	ss->sum_y += ss->bw_data[i];
	84	j = ss->head + i;
	85	if (j >= ss->dur)
	86	j -= ss->dur;
	87	if (ss->state & __FIO_SS_IOPS)
	88	ss->sum_xy += i * ss->iops_data[j];
	89	else
	90	ss->sum_xy += i * ss->bw_data[j];
	91	}
	92	} else { /* easy to update the sums */
	93	ss->sum_y -= ss->oldest_y;
	94	ss->sum_y += new_val;
	95	ss->sum_xy = ss->sum_xy - ss->sum_y + ss->dur * new_val;
	96	}
	97
	98	if (ss->state & __FIO_SS_IOPS)
	99	ss->oldest_y = ss->iops_data[ss->head];
	100	else
	101	ss->oldest_y = ss->bw_data[ss->head];
	102
	103	/*
	104	* calculate slope as (sum_xy - sum_x * sum_y / n) / (sum_(x^2)
	105	* - (sum_x)^2 / n) This code assumes that all x values are
	106	* equally spaced when they are often off by a few milliseconds.
	107	* This assumption greatly simplifies the calculations.
	108	*/
	109	ss->slope = (ss->sum_xy - (double) ss->sum_x * ss->sum_y / ss->dur) /
	110	(ss->sum_x_sq - (double) ss->sum_x * ss->sum_x / ss->dur);
	111	if (ss->state & __FIO_SS_PCT)
	112	ss->criterion = 100.0 * ss->slope / (ss->sum_y / ss->dur);
	113	else
	114	ss->criterion = ss->slope;
	115
	116	dprint(FD_STEADYSTATE, "sum_y: %llu, sum_xy: %llu, slope: %f, "
	117	"criterion: %f, limit: %f\n",
	118	ss->sum_y, ss->sum_xy, ss->slope,
	119	ss->criterion, ss->limit);
	120
	121	result = ss->criterion * (ss->criterion < 0.0 ? -1.0 : 1.0);
	122	if (result < ss->limit)
	123	return true;
	124	}
	125
	126	ss->tail = (ss->tail + 1) % ss->dur;
	127	if (ss->tail <= ss->head)
	128	ss->head = (ss->head + 1) % ss->dur;
	129
	130	return false;
	131	}
	132
	133	static bool steadystate_deviation(unsigned long iops, unsigned long bw,
	134	struct thread_data *td)
	135	{
	136	int i;
	137	double diff;
	138	double mean;
	139
	140	struct steadystate_data *ss = &td->ss;
	141
	142	ss->bw_data[ss->tail] = bw;
	143	ss->iops_data[ss->tail] = iops;
	144
	145	if (ss->tail < ss->head \|\| (ss->tail - ss->head == ss->dur - 1)) {
	146	if (ss->sum_y == 0) { /* first time through */
	147	for(i = 0; i < ss->dur; i++)
	148	if (ss->state & __FIO_SS_IOPS)
	149	ss->sum_y += ss->iops_data[i];
	150	else
	151	ss->sum_y += ss->bw_data[i];
	152	} else { /* easy to update the sum */
	153	ss->sum_y -= ss->oldest_y;
	154	if (ss->state & __FIO_SS_IOPS)
	155	ss->sum_y += ss->iops_data[ss->tail];
	156	else
	157	ss->sum_y += ss->bw_data[ss->tail];
	158	}
	159
	160	if (ss->state & __FIO_SS_IOPS)
	161	ss->oldest_y = ss->iops_data[ss->head];
	162	else
	163	ss->oldest_y = ss->bw_data[ss->head];
	164
	165	mean = (double) ss->sum_y / ss->dur;
	166	ss->deviation = 0.0;
	167
	168	for (i = 0; i < ss->dur; i++) {
	169	if (ss->state & __FIO_SS_IOPS)
	170	diff = ss->iops_data[i] - mean;
	171	else
	172	diff = ss->bw_data[i] - mean;
	173	ss->deviation = max(ss->deviation, diff * (diff < 0.0 ? -1.0 : 1.0));
	174	}
	175
	176	if (ss->state & __FIO_SS_PCT)
	177	ss->criterion = 100.0 * ss->deviation / mean;
	178	else
	179	ss->criterion = ss->deviation;
	180
	181	dprint(FD_STEADYSTATE, "sum_y: %llu, mean: %f, max diff: %f, "
	182	"objective: %f, limit: %f\n",
	183	ss->sum_y, mean, ss->deviation,
	184	ss->criterion, ss->limit);
	185
	186	if (ss->criterion < ss->limit)
	187	return true;
	188	}
	189
	190	ss->tail = (ss->tail + 1) % ss->dur;
	191	if (ss->tail <= ss->head)
	192	ss->head = (ss->head + 1) % ss->dur;
	193
	194	return false;
	195	}
	196
	197	void steadystate_check(void)
	198	{
	199	int i, j, ddir, prev_groupid, group_ramp_time_over = 0;
	200	unsigned long rate_time;
	201	struct thread_data td, td2;
	202	struct timeval now;
	203	unsigned long group_bw = 0, group_iops = 0;
	204	unsigned long long td_iops;
	205	unsigned long long td_bytes;
	206	bool ret;
	207
	208	prev_groupid = -1;
	209	for_each_td(td, i) {
	210	struct steadystate_data *ss = &td->ss;
	211
	212	if (!ss->dur \|\| td->runstate <= TD_SETTING_UP \|\|
	213	td->runstate >= TD_EXITED \|\| (ss->state & __FIO_SS_ATTAINED))
	214	continue;
	215
	216	td_iops = 0;
	217	td_bytes = 0;
	218	if (!td->o.group_reporting \|\|
	219	(td->o.group_reporting && td->groupid != prev_groupid)) {
	220	group_bw = 0;
	221	group_iops = 0;
	222	group_ramp_time_over = 0;
	223	}
	224	prev_groupid = td->groupid;
	225
	226	fio_gettime(&now, NULL);
	227	if (ss->ramp_time && !(ss->state & __FIO_SS_RAMP_OVER)) {
	228	/*
	229	* Begin recording data one second after ss->ramp_time
	230	* has elapsed
	231	*/
	232	if (utime_since(&td->epoch, &now) >= (ss->ramp_time + 1000000L))
	233	ss->state \|= __FIO_SS_RAMP_OVER;
	234	}
	235
	236	td_io_u_lock(td);
	237	for (ddir = DDIR_READ; ddir < DDIR_RWDIR_CNT; ddir++) {
	238	td_iops += td->io_blocks[ddir];
	239	td_bytes += td->io_bytes[ddir];
	240	}
	241	td_io_u_unlock(td);
	242
	243	rate_time = mtime_since(&ss->prev_time, &now);
	244	memcpy(&ss->prev_time, &now, sizeof(now));
	245
	246	/*
	247	* Begin monitoring when job starts but don't actually use
	248	* data in checking stopping criterion until ss->ramp_time is
	249	* over. This ensures that we will have a sane value in
	250	* prev_iops/bw the first time through after ss->ramp_time
	251	* is done.
	252	*/
	253	if (ss->state & __FIO_SS_RAMP_OVER) {
	254	group_bw += 1000 * (td_bytes - ss->prev_bytes) / rate_time;
	255	group_iops += 1000 * (td_iops - ss->prev_iops) / rate_time;
	256	++group_ramp_time_over;
	257	}
	258	ss->prev_iops = td_iops;
	259	ss->prev_bytes = td_bytes;
	260
	261	if (td->o.group_reporting && !(ss->state & __FIO_SS_DATA))
	262	continue;
	263
	264	/*
	265	* Don't begin checking criterion until ss->ramp_time is over
	266	* for at least one thread in group
	267	*/
	268	if (!group_ramp_time_over)
	269	continue;
	270
	271	dprint(FD_STEADYSTATE, "steadystate_check() thread: %d, "
	272	"groupid: %u, rate_msec: %ld, "
	273	"iops: %lu, bw: %lu, head: %d, tail: %d\n",
	274	i, td->groupid, rate_time, group_iops,
	275	group_bw, ss->head, ss->tail);
	276
	277	if (td->o.ss & __FIO_SS_SLOPE)
	278	ret = steadystate_slope(group_iops, group_bw, td);
	279	else
	280	ret = steadystate_deviation(group_iops, group_bw, td);
	281
	282	if (ret) {
	283	if (td->o.group_reporting) {
	284	for_each_td(td2, j) {
	285	if (td2->groupid == td->groupid) {
	286	td2->ss.state \|= __FIO_SS_ATTAINED;
	287	fio_mark_td_terminate(td2);
	288	}
	289	}
	290	} else {
	291	ss->state \|= __FIO_SS_ATTAINED;
	292	fio_mark_td_terminate(td);
	293	}
	294	}
	295	}
	296	}
	297
	298	int td_steadystate_init(struct thread_data *td)
	299	{
	300	struct steadystate_data *ss = &td->ss;
	301	struct thread_options *o = &td->o;
	302	struct thread_data *td2;
	303	int j;
	304
	305	memset(ss, 0, sizeof(*ss));
	306
	307	if (o->ss_dur) {
	308	steadystate_enabled = true;
	309	o->ss_dur /= 1000000L;
	310
	311	/* put all steady state info in one place */
	312	ss->dur = o->ss_dur;
	313	ss->limit = o->ss_limit.u.f;
	314	ss->ramp_time = o->ss_ramp_time;
	315
	316	ss->state = o->ss;
	317	if (!td->ss.ramp_time)
	318	ss->state \|= __FIO_SS_RAMP_OVER;
	319
	320	ss->sum_x = o->ss_dur * (o->ss_dur - 1) / 2;
	321	ss->sum_x_sq = (o->ss_dur - 1) * (o->ss_dur) * (2*o->ss_dur - 1) / 6;
	322
	323	td->ts.ss = ss;
	324	}
	325
	326	/* make sure that ss options are consistent within reporting group */
	327	for_each_td(td2, j) {
	328	if (td2->groupid == td->groupid) {
	329	struct steadystate_data *ss2 = &td2->ss;
	330
	331	if (ss2->dur != ss->dur \|\|
	332	ss2->limit != ss->limit \|\|
	333	ss2->ramp_time != ss->ramp_time \|\|
	334	ss2->state != ss->state \|\|
	335	ss2->sum_x != ss->sum_x \|\|
	336	ss2->sum_x_sq != ss->sum_x_sq) {
	337	td_verror(td, EINVAL, "job rejected: steadystate options must be consistent within reporting groups");
	338	return 1;
	339	}
	340	}
	341	}
	342
	343	return 0;
	344	}
	345
	346	unsigned long long steadystate_bw_mean(struct steadystate_data *ss)
	347	{
	348	int i;
	349	unsigned long long sum;
	350
	351	for (i = 0, sum = 0; i < ss->dur; i++)
	352	sum += ss->bw_data[i];
	353
	354	return sum / ss->dur;
	355	}
	356
	357	unsigned long long steadystate_iops_mean(struct steadystate_data *ss)
	358	{
	359	int i;
	360	unsigned long long sum;
	361
	362	for (i = 0, sum = 0; i < ss->dur; i++)
	363	sum += ss->iops_data[i];
	364
	365	return sum / ss->dur;
	366	}