From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Frederic Sowa Subject: Re: Does IPv6 support Jumbograms ? Date: Thu, 10 Apr 2014 15:28:42 +0200 Message-ID: <20140410132842.GI27255@order.stressinduktion.org> References: <5345A2B3.7040602@gmail.com> <1397079665.16584.17.camel@edumazet-glaptop2.roam.corp.google.com> <20140409223546.GH27255@order.stressinduktion.org> <1397090170.16584.21.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Francois WELLENREITER , netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from order.stressinduktion.org ([87.106.68.36]:35113 "EHLO order.stressinduktion.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030658AbaDJN2o (ORCPT ); Thu, 10 Apr 2014 09:28:44 -0400 Content-Disposition: inline In-Reply-To: <1397090170.16584.21.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Apr 09, 2014 at 05:36:10PM -0700, Eric Dumazet wrote: > On Thu, 2014-04-10 at 00:35 +0200, Hannes Frederic Sowa wrote: > > On Wed, Apr 09, 2014 at 02:41:05PM -0700, Eric Dumazet wrote: > > > What do you mean by blocked ? > > > > > > Please give more details (kernel version, exact mtu...), because it > > > should not happen ! > > > > > > # ifconfig lo mtu 100000 > > > # scp -6 vmlinux edumazet@ip6-localhost:/tmp > > > Password: > > > vmlinux > > > 100% 24MB 23.5MB/s 00:00 > > > # ls -l /tmp/vmlinux > > > -rwxr-xr-x 1 edumazet eng 24668915 Apr 9 14:37 /tmp/vmlinux > > > > I couldn't test it on my development system with a recent net-next kernel > > yet, but on my laptop with a distribution 3.13.9 kernel this happened too. > > Oh well, it seems ip6_mtu() needs to cap mtu to max mtu for non > jumbograms... > > - return mtu; > + return min_t(unsigned int, mtu, IP6_MAX_MTU); > > #define IP6_MAX_MTU (65535 + 40) I thought ip6_default_advmss will deal with this which correctly limits the mtu. Capping dst_mtu would make it harder to implement jumbograms some day. I'll look into it, thank you.