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ceph: track average r/w/m latency

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

Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
This commit is contained in:
Venky Shankar 2022-03-08 07:42:17 -05:00 committed by Ilya Dryomov
parent 8d728c769f
commit 367290e635
2 changed files with 15 additions and 13 deletions
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27
fs/ceph/metric.c
View File

@ -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,
ktime_t *sq_sump, ktime_t lat)
static inline void __update_mean_and_stdev(ktime_t total, ktime_t *lavg,
ktime_t *sq_sump, ktime_t lat)
{
ktime_t avg, sq;
ktime_t avg;
if (unlikely(total == 1))
return;
/* 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;
if (unlikely(total == 1)) {
*lavg = lat;
} else {
/* the sq is (lat - old_avg) * (lat - new_avg) */
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);
}

1
fs/ceph/metric.h
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@ -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;