Subject: Re: atomic operations bottleneck in the IPv6 stack

From: Hannes Frederic Sowa <[email-masked]>
Date: Wed, 10 Dec 2014 18:58:30 +0100

On Mi, 2014-12-10 at 18:16 +0100, Hannes Frederic Sowa wrote:
> On Mi, 2014-12-10 at 16:56 +0000, [email-masked] wrote:
> > 
> > It seems to me that the atomic operations on the IPv6 forwarding path
> > are a bottleneck and they are not scalable with the number of cores.
> > Am I right? What improvements can be brought to the IPv6 kernel code
> > to make it less dependent of atomic operations/variables?
> 
> For a starter, something like the following commit:
> 
> commit d26b3a7c4b3b26319f18bb645de93eba8f4bdcd5
> Author: Eric Dumazet <[email-masked]>
> Date:   Tue Jul 31 05:45:30 2012 +0000
> 
>     ipv4: percpu nh_rth_output cache

Actually, we should be able to remove the atomics in input and
forwarding path by just relying on RCU. I'll have a look.

Bye,
Hannes