From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: [PATCH net-next] ipv6: implement rt_genid_bump_ipv6 with fn_sernum and remove rt6i_genid Date: Thu, 11 Sep 2014 10:30:07 +0200 Message-ID: <1410424207.2672.21.camel@localhost> References: <1410267519.27979.31.camel@localhost> <130f98f49b1b90a30908bfda8f01109c91edfe1c.1410341451.git.hannes@stressinduktion.org> <20140910.130929.247064282043941043.davem@davemloft.net> 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: David Miller Return-path: Received: from out4-smtp.messagingengine.com ([66.111.4.28]:53495 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753406AbaIKIaL (ORCPT ); Thu, 11 Sep 2014 04:30:11 -0400 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by gateway2.nyi.internal (Postfix) with ESMTP id B6BD720AF6 for ; Thu, 11 Sep 2014 04:30:10 -0400 (EDT) In-Reply-To: <20140910.130929.247064282043941043.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: 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. Thanks, Hannes