From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: UDP path MTU discovery Date: Tue, 30 Mar 2010 08:16:27 +0200 Message-ID: <20100330061627.GM20695@one.firstfloor.org> References: <1269561751.2891.8.camel@ilion> <877how25kx.fsf@basil.nowhere.org> <4BB0DCF6.9020401@hp.com> <20100329201431.GH20695@one.firstfloor.org> <20100329205035.GA32656@laped.iglesias.mooo.com> <4BB11510.9000302@hp.com> <1269898152.1958.86.camel@edumazet-laptop> <20100330052044.GJ20695@one.firstfloor.org> <1269929168.1958.94.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andi Kleen , "Templin, Fred L" , Rick Jones , "Edgar E. Iglesias" , Glen Turner , "netdev@vger.kernel.org" To: Eric Dumazet Return-path: Received: from one.firstfloor.org ([213.235.205.2]:51630 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755559Ab0C3GQ3 (ORCPT ); Tue, 30 Mar 2010 02:16:29 -0400 Content-Disposition: inline In-Reply-To: <1269929168.1958.94.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: > > Right now there is no right socket option to set the path mtu. We > > have a IP_MTU option, but it only works for getting the MTU. > > That's because the PMTU is in the routing cache entry and shared > > by multiple sockets. Presumably one could add a special case > > with an MTU in the socket overriding the one in the destination entry. > > We have IP_MTU_DISCOVER option with four existing values I think you would just need a sk->pmtu and a option to set/unset it Or perhaps just a flag that clamps to 1280? Then the existing mtu discover options would be sufficient. -Andi -- ak@linux.intel.com -- Speaking for myself only.