netdev - Re: [PATCH nf-next-2.6 2/2] conntrack: per

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Message-ID: <4C0E53C4.7090308@trash.net>
Date:	Tue, 08 Jun 2010 16:29:24 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Changli Gao <xiaosuo@...il.com>,
	Netfilter Developers <netfilter-devel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH nf-next-2.6 2/2] conntrack: per_cpu untracking

On 04.06.2010 22:15, Eric Dumazet wrote:
> NOTRACK makes all cpus share a cache line on nf_conntrack_untracked
> twice per packet, slowing down performance.
> 
> This patch converts it to a per_cpu variable.
> 
> We assume same cpu is used for a given packet, entering and exiting the
> NOTRACK state.

That doesn't seem to be a valid assumption, the conntrack entry is
attached to the skb and processing in the output path might get
preempted and rescheduled to a different CPU.
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