From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: low vxlan throughput with tso enabled Date: Tue, 03 Feb 2015 08:36:15 -0800 Message-ID: <54D0F8FF.1090204@hp.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Cc: svens@stackframe.org, Vittorio Curcio To: Reiner Herrmann , netdev@vger.kernel.org Return-path: Received: from g4t3426.houston.hp.com ([15.201.208.54]:34029 "EHLO g4t3426.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965742AbbBCQgS (ORCPT ); Tue, 3 Feb 2015 11:36:18 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 02/03/2015 07:50 AM, Reiner Herrmann wrote: > I have a vxlan tunnel established between two network interfaces, which > both have a MTU of 1500. The vxlan interfaces have the same MTU. > With TSO enabled, I observe low throughput with TCP connections (<100 > kB/s). > Disabling TSO works around this issue and throughput is as expected. > Can someone please explain how TSO is influencing the tunnel to cause > such a difference? I've been under the impression that one generally wants the MTU of a tunnel interface to be no more than the MTU of the physical interface over which it runs, less the size of the encapsulation headers used by the tunnel. What happens when you make the MTU of the tunnel interface 1400 bytes instead of 1500? rick jones