Re: [PATCH nf-next-2.6 2/2] conntrack: per_cpu untracking

Eric Dumazet
2010-06-08T14:52:13Z

Le mardi 08 juin 2010 à 16:29 +0200, Patrick McHardy a écrit :
> 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.

Thats unfortunate.

Ok, only choice then is to not change refcount on the untracked ct, and
keep a shared (read only after setup time) untrack structure.

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