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authorVenky Shankar <vshankar@redhat.com>2022-03-08 07:42:17 -0500
committerIlya Dryomov <idryomov@gmail.com>2022-03-21 13:35:16 +0100
commit367290e6355ce13c17d17f3ec1075beb7ca3224a (patch)
treed7070336e2127c775ee163ce696f02da7e1117cc /fs/ceph/metric.c
parent8d728c769fd8e5aaaea36288741a4e3493111816 (diff)
ceph: track average r/w/m latency
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>
Diffstat (limited to 'fs/ceph/metric.c')
-rw-r--r--fs/ceph/metric.c29
1 files changed, 15 insertions, 14 deletions
diff --git a/fs/ceph/metric.c b/fs/ceph/metric.c
index 454d2c93208e..14b6af48b611 100644
--- a/fs/ceph/metric.c
+++ b/fs/ceph/metric.c
@@ -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;
-
- 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;
+ ktime_t avg;
+
+ 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);
}