Re: [PATCH] net: reset skb queue mapping when rx'ing over tunnel

[Eric Dumazet <eric.dumazet@gmail.com>]

Le vendredi 24 septembre 2010 à 09:18 -0700, Tom Herbert a écrit :
> > Hmm...
> >
> > This would need to be reverted later when tunnels are updated to be
> > multiqueue aware ? I made an attempt with GRE some days ago.
> >
> > I dont understand why this patch is needed, since get_rps_cpu() has a
> > check anyway
> >
> I think the skb queue_mapping should correspond to a queue in the
> skb's device as an invariant.  In the case that an skb's device is
> change from a multiqueue device to single queue device (like GRE), the
> inconsistency in the queue_mapping is fairly innocuous, we get one
> warning but will pretty much take the unlikely branch for GRE packets
> then on.  But imagine a case where skb's device was change from one
> multiqueue device to another, but the queue mapping was not also
> updated.  This  would cause poor weighting in get_rps_cpus.  For
> example, if the new device had fewer queues than the old one,
> get_rps_cpu will bias toward using queue 0's rps mask.

I believe your patch is fine. Thanks

Acked-by: Eric Dumazet <eric.dumazet@gmail.com>