Commit 367290e6 authored by Venky Shankar's avatar Venky Shankar Committed by Ilya Dryomov
Browse files

ceph: track average r/w/m latency 



Make the math a bit simpler to understand (should not
affect execution speeds).

Signed-off-by: default avatarVenky Shankar <vshankar@redhat.com>
Reviewed-by: default avatarXiubo Li <xiubli@redhat.com>
Signed-off-by: default avatarIlya Dryomov <idryomov@gmail.com>
parent 8d728c76

fs/ceph/metric.c

+15 −14
Original line number Diff line number Diff line
@@ -249,6 +249,7 @@ int ceph_metric_init(struct ceph_client_metric *m) 
		metric->size_max = 0;

		metric->total = 0;

		metric->latency_sum = 0;

		metric->latency_avg = 0;

		metric->latency_sq_sum = 0;

		metric->latency_min = KTIME_MAX;

		metric->latency_max = 0;
@@ -306,20 +307,19 @@ void ceph_metric_destroy(struct ceph_client_metric *m) 
		max = new;			\

}



static inline void __update_stdev(ktime_t total, ktime_t lsum,

static inline void __update_mean_and_stdev(ktime_t total, ktime_t *lavg,

					   ktime_t *sq_sump, ktime_t lat)

{

	ktime_t avg, sq;



	if (unlikely(total == 1))

		return;

	ktime_t avg;



	if (unlikely(total == 1)) {

		*lavg = lat;

	} else {

		/* the sq is (lat - old_avg) * (lat - new_avg) */

	avg = DIV64_U64_ROUND_CLOSEST((lsum - lat), (total - 1));

	sq = lat - avg;

	avg = DIV64_U64_ROUND_CLOSEST(lsum, total);

	sq = sq * (lat - avg);

	*sq_sump += sq;

		avg = *lavg + div64_s64(lat - *lavg, total);

		*sq_sump += (lat - *lavg)*(lat - avg);

		*lavg = avg;

	}

}



void ceph_update_metrics(struct ceph_metric *m,
@@ -338,6 +338,7 @@ void ceph_update_metrics(struct ceph_metric *m, 
	METRIC_UPDATE_MIN_MAX(m->size_min, m->size_max, size);

	m->latency_sum += lat;

	METRIC_UPDATE_MIN_MAX(m->latency_min, m->latency_max, lat);

	__update_stdev(total, m->latency_sum, &m->latency_sq_sum, lat);

	__update_mean_and_stdev(total, &m->latency_avg,	&m->latency_sq_sum,

				lat);

	spin_unlock(&m->lock);

}

fs/ceph/metric.h

+1 −0
Original line number Diff line number Diff line
@@ -137,6 +137,7 @@ struct ceph_metric { 
	u64 size_min;

	u64 size_max;

	ktime_t latency_sum;

	ktime_t latency_avg;

	ktime_t latency_sq_sum;

	ktime_t latency_min;

	ktime_t latency_max;