linux-kernel - Re: [NETFILTER] early

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Message-ID: <4682523F.6000002@trash.net>
Date:	Wed, 27 Jun 2007 14:04:15 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Vasily Averin <vvs@...ru>
CC:	netfilter-devel@...ts.netfilter.org, rusty@...tcorp.com.au,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Eric Dumazet <dada1@...mosbay.com>,
	Jan Engelhardt <jengelh@...putergmbh.de>,
	"David S. Miller" <davem@...emloft.net>, devel@...nvz.org
Subject: Re: [NETFILTER] early_drop() imrovement (v4)

Patrick McHardy wrote:
> Vasily Averin wrote:
> 
>>When the number of conntracks is reached nf_conntrack_max limit, early_drop()
>>tries to free one of already used conntracks. If it does not find any conntracks
>>that may be freed, it leads to transmission errors.
>>In current implementation the conntracks are searched in one hash bucket only.
>>It have some drawbacks: if used hash bucket is empty we have not any chances to
>>find something. On the other hand the hash bucket can contain a huge number of
>>conntracks and its check can last a long time.
>>The proposed patch limits the number of checked conntracks and allows to search
>>conntracks in other hash buckets. As result in any case the search will have the
>>same chances to free one of the conntracks and the check will not lead to long
>>delays.
> 
> 
> 
> Thanks Vasily. I have some patches queued to convert all conntrack
> hashes to hlists, which conflict with your patches. They need a bit
> more work, I'll integrate your changes on top of them once I'm done.


I've added this patch to my tree at

http://people.netfilter.org/kaber/nf-2.6.23.git/

I've joined the two loops from your patch since that avoids an
otherwise useless function and doesn't take the lock up to 8
times in a row.


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