netdev - Re: [PATCH 0/5] netfilter updates for net-next (upcoming 3.5), batch 2

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Message-ID: <20120514082131.GA9524@1984>
Date:	Mon, 14 May 2012 10:21:31 +0200
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	David Miller <davem@...emloft.net>
Cc:	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 0/5] netfilter updates for net-next (upcoming 3.5),
 batch 2

On Wed, May 09, 2012 at 06:11:19PM -0400, David Miller wrote:
> From: pablo@...filter.org
> Date: Wed,  9 May 2012 13:33:03 +0200
> 
> > This is a second batch of netfilter updates for net-next, they contain:
> > 
> > * The new HMARK target from Hans Schillstrom. It took lots of spins
> >   to get this into shape. This target provides a hash-based packet / flow
> >   pre-classifier for iptables that can be used to distribute packets
> >   / flows between uplinks and backend servers. It provides to modes, one
> >   that relies on conntrack, and one that is stateless per-packet.
> > 
> > * Byte-based cost calculation for the hashlimit match, to detect when
> >   a host consumes more bandwidth than expected. This patch from Florian
> >   Westphal.
> > 
> > You can pull these changes from:
> > 
> > git://1984.lsi.us.es/net-next
> 
> Pulled.
> 
> Two suggested improvements:
> 
> 1) The HMARK hash is quite expensive, because it uses a modulus.
> 
>    Consider adjusting it to use the usual trick:
> 
> 	((u64)(HASH_VAL * HASH_SIZE)) >> 32
> 
>    so that this can be a multiply instead of a modulus.

I'll enqueue the patch attached for this. Thanks for spotting this.

View attachment "0001-netfilter-xt_HMARK-modulus-is-expensive-for-hash-cal.patch" of type "text/x-diff" (965 bytes)