Re: [PATCH] net_sched: accurate bytes/packets stats/rates

* Eric Dumazet | 2011-01-17 08:17:49 [+0100]:

Hmm, considering qdisc stats are not used in kernel (only updated and
reported to tc users) it seems to me counting arrival instead of
departure rates is mostly useless for the user, if drops are ignored.

(I am not speaking of direct drops, when we try to enqueue() this skb,
but later ones, when another skb is enqueued and we drop a previously
enqueued skb)

User really wants to see the effective departure rate, to check its
qdisc parameters in respect with kernel ones (HZ=100/1000, HIGH res
timers off/on, ...)

Arrival rates are of litle use. However, it might be good to have a
second "bstats" only for dropped packets/bytes, or extend bstats in a
compatible way (maybe adding fields to the end of structure)

Sure, qdiscs like CHOKe, SFQ, pfifo_head are only analyzable with this kind of
additional information. E.g. pfifo_head currently provides no statistic that
the queue length is possible underestimated and tunning is required.

Hagen