linux-kernel - Re: [NETFILTER] early

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Message-ID: <46811292.1010501@sw.ru>
Date:	Tue, 26 Jun 2007 17:20:18 +0400
From:	Vasily Averin <vvs@...ru>
To:	Patrick McHardy <kaber@...sh.net>
CC:	Eric Dumazet <dada1@...mosbay.com>,
	"David S. Miller" <davem@...emloft.net>,
	netfilter-devel@...ts.netfilter.org, rusty@...tcorp.com.au,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	devel@...nvz.org
Subject: Re: [NETFILTER] early_drop() imrovement (v3)

Patrick McHardy wrote:

Patrick, thank you for your tips, I'll remake the patch.

> I don't like the NF_CT_PER_BUCKET constant. First of all, each
> conntrack is hashed twice, so its really only 1/2 of the average
> conntracks per bucket. Secondly, its only a default and many
> people use nf_conntrack_max = nf_conntrack_htable_size / 2, so
> using this constant for early_drop seems wrong.

> Perhaps make it 2 * nf_conntrack_max / nf_conntrack_htable_size
> or even add a nf_conntrack_eviction_range sysctl.

IMHO The number of conntracks checked in early_drop() have following restrictions:
- it should be not too low -- to decrease chances of transmission failures,
- it should be limited by some reasonable value -- to prevent long check delays.

Also I believe it makes sense to have it constant (how about NF_CT_EVICTION
name?) -- to have the same behaviour on various nodes. However I doubt strongly
that anybody will want to change this value. Do you think it is really required?

thank you,
	Vasily Averin
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