From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: atomic operations bottleneck in the IPv6 stack Date: Wed, 10 Dec 2014 18:58:30 +0100 Message-ID: <1418234310.24395.5.camel@redhat.com> References: <1418231763.24395.2.camel@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" , "R89243@freescale.com" , Madalin-Cristian Bucur , "Razvan.Ungureanu@freescale.com" To: "cristian.bercaru@freescale.com" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:45070 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932479AbaLJS3y (ORCPT ); Wed, 10 Dec 2014 13:29:54 -0500 In-Reply-To: <1418231763.24395.2.camel@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mi, 2014-12-10 at 18:16 +0100, Hannes Frederic Sowa wrote: > On Mi, 2014-12-10 at 16:56 +0000, cristian.bercaru@freescale.com 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 > 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