From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH net-next] ipv6: implement rt_genid_bump_ipv6 with fn_sernum and remove rt6i_genid Date: Thu, 11 Sep 2014 08:22:33 -0400 Message-ID: <54119409.20907@gmail.com> References: <1410267519.27979.31.camel@localhost> <130f98f49b1b90a30908bfda8f01109c91edfe1c.1410341451.git.hannes@stressinduktion.org> <20140910.130929.247064282043941043.davem@davemloft.net> <1410424207.2672.21.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, eric.dumazet@gmail.com, nicolas.dichtel@6wind.com To: Hannes Frederic Sowa , David Miller Return-path: Received: from mail-qc0-f171.google.com ([209.85.216.171]:39949 "EHLO mail-qc0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754271AbaIKMWg (ORCPT ); Thu, 11 Sep 2014 08:22:36 -0400 Received: by mail-qc0-f171.google.com with SMTP id x3so21147388qcv.16 for ; Thu, 11 Sep 2014 05:22:35 -0700 (PDT) In-Reply-To: <1410424207.2672.21.camel@localhost> Sender: netdev-owner@vger.kernel.org List-ID: On 09/11/2014 04:30 AM, Hannes Frederic Sowa wrote: > On Mi, 2014-09-10 at 13:09 -0700, David Miller wrote: >> From: Hannes Frederic Sowa >> Date: Wed, 10 Sep 2014 11:31:28 +0200 >> >>> In case we need to force the sockets to relookup the routes we now >>> increase the fn_sernum on all fibnodes in the routing tree. This is a >>> costly operation but should only happen if we have major routing/policy >>> changes in the kernel (e.g. manual route adding/removal, xfrm policy >>> changes). >> >> Core routers can update thousands of route updates per second, and they >> do this via what you refer to as "manual route adding/removal". > > Sorry, I was too unspecific here. Route changes because of address > removal/addition on the local stack. > > The reason why we do the bump_id here is that we want to flush all the > socket caches in case we have either lost or gained access to a new > source address. > > If you think about e.g. BGP routers which update lots of routes, they > aren't affected and the flush won't happen on every route change. > >> I don't think we want to put such a scalability problem into the tree. >> >> There has to be a lightweight way to address this. > > I am still investigating why this bump_id actually happened. Seems the > reason is only sctp ontop of IPv6 and maybe we can build something much > more lightweight, yes. No. It was proven that a regular TCP socket could continue sending traffic using an address that was removed. -vlad > > Thanks, > Hannes > > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >