From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Thery Subject: Re: [Devel] Re: network namespace ipv6 perfs Date: Mon, 03 Mar 2008 18:27:50 +0100 Message-ID: <47CC3516.7030901@bull.net> References: <47CC0920.6000005@fr.ibm.com> <47CC0E3B.1040809@bull.net> <47CC114F.8050104@openvz.org> <939d53060803030704g5d693c19i34061f1a896d91cd@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Daniel Lezcano , Linux Containers , Linux Netdev List , Denis Lunev To: Benjamin Thery , Pavel Emelyanov Return-path: Received: from ecfrec.frec.bull.fr ([129.183.4.8]:50181 "EHLO ecfrec.frec.bull.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762220AbYCCR1k (ORCPT ); Mon, 3 Mar 2008 12:27:40 -0500 In-Reply-To: <939d53060803030704g5d693c19i34061f1a896d91cd@mail.gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Benjamin Thery wrote: > On Mon, Mar 3, 2008 at 3:55 PM, Pavel Emelyanov wrote: >> Benjamin Thery wrote: >> > Daniel Lezcano wrote: >> >> Hi, >> >> >> >> Some performance tests was made by Benjamin to watch out the impact of >> >> the network namespace. The good news is there is no impact when used >> >> with or without namespaces. That has been checked using a real network >> >> device inside a network namespace. >> >> >> >> These results are consistent with the ones previously made for ipv4. >> >> >> >> http://lxc.sourceforge.net/network/bench_ipv6_graph.php >> >> >> >> Thanks to Benjamin who did all the performance tests :) >> > >> > In these results, may be, there is one thing that should be explained. >> > It is the CPU utilization overhead in the 'veth' case. >> > >> > Compared to physical devices or macvlan, veth interfaces don't benefit >> > from hardware offloading mechanisms: i.e. checksums have to be computed >> > by the soft. That explains the big overhead in CPU utilization when >> >> You can tune the veth devices not to account checksum when unnecessary. > > Oh. This is interesting. > > You mean with ethtool -K rx/tx? > I will give it a try. Pavel, I had no luck with "ethtool -K veth0 rx on tx on". On my testbed, with these options TCP drops packets (trying to establish a ssh connection between init and child namespace). Then, I tested "ethtool -K veth0 rx on tx off". This time TCP (and netperf) work, but I see no difference in CPU load compared to the case without offloading. Can I tune veth differently? (BTW, I run netperf between a child namespace on host A and netserv on host B. The stream goes through the following interface: veth1 on A -> veth0 on A -> eth1 on A -> ("real network") -> eth1 on B) Benjamin > >> >> > using this kind of virtual interface. >> > >> > Benjamin >> > >> >> Regards >> >> -- Daniel >> >> > >> -- >> 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 >> > > -- B e n j a m i n T h e r y - BULL/DT/Open Software R&D http://www.bull.com