netdev - Re: [patch 0/6] netfilter: ctnetlink allocation improvement

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Date:	Tue, 17 Mar 2009 10:49:00 +0100
From:	Pablo Neira Ayuso <pablo@...filter.org>
To:	Holger Eitzenberger <holger@...zenberger.org>
CC:	Patrick McHardy <kaber@...sh.net>,
	David Miller <davem@...emloft.net>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [patch 0/6] netfilter: ctnetlink allocation improvement

Hi Holger,

Holger Eitzenberger wrote:
> what follows is a small patchset against net-next-2.6 which tries to
> improve the way ctnetlink events are allocated.  By allocating the
> ctnetlink skbs roughly the size of the message we prevent the skb from
> later being reallocated in netlink_trim().

I have a similar patch here that I sent time ago, I'll send it again, I
think that we can merge your patches and mine.

> Though I haven't got any hard performance numbers yet I think this
> might introduce a noticable performance gain.

I'm not sure about this. Instead, I noticed with oprofile that we spend
more cycles to calculate the message size. I think it's more like a
trade-off, reducing the message size to what we need reduces the chances
to hit ENOBUFS.

> I also have to introduce NF_CT_HELPER_NAME_LEN as an upper limit for
> the conntrack protcol helper names, which is not much of a problem
> because all names in mainline are actually shorter than that.

I'm fine with the helper size change. Actually the current size of 30
bytes doesn't make too much sense.

-- 
"Los honestos son inadaptados sociales" -- Les Luthiers
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