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Re: Fw: hfsc and huge set of rules

To: devik <devik@xxxxxx>
Subject: Re: Fw: hfsc and huge set of rules
From: Patrick McHardy <kaber@xxxxxxxxx>
Date: Sun, 01 Aug 2004 19:56:04 +0200
Cc: "David S. Miller" <davem@xxxxxxxxxx>, hadi@xxxxxxxxxx, netdev@xxxxxxxxxxx, tomasz.paszkowski@xxxxxxxx
In-reply-to: <Pine.LNX.4.33.0407301752250.1421-100000@devix>
References: <Pine.LNX.4.33.0407301752250.1421-100000@devix>
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devik wrote:

Also IIRC class lookup is done before each remove. With
hashing size a few tens of buckets the complexity
starts to be very near to O(n^2).
I think the hash size of HTB, HFSC and CBQ should be increased,
the hash function performs well even with 2^16. With HFSC using
many classes doesn't scale well right now, but with the rbtree patches
it will.

Regards
Patrick

devik

On Fri, 30 Jul 2004, Patrick McHardy wrote:

David S. Miller wrote:
Looks like qdisc destruction has some expensive algorithms.
Any quick ideas about the root culprit at least in the hfsc
case?  He says htb does it too.
hfsc_destroy_qdisc takes O(n) time wrt. the number of classes,
but 5-6 seconds is still long. If all these classes contain inner
qdiscs other than the default, I guess removing the classes from
dev->qdisc_list in qdisc_destroy takes up most of the time, with
n O(n) operations. The __qdisc_destroy rcu callback also calls
reset before destroy, I don't know any qdisc where this is really
neccessary. Without inner qdiscs, I need to see the script first to
judge what's going wrong. Tomasz ?

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