From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Priebe - Profihost AG Subject: unstable 10GBE performance with recent kernels (> 3.0.X) Date: Mon, 18 Jun 2012 11:22:20 +0200 Message-ID: <4FDEF34C.808@profihost.ag> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit To: Linux Netdev List Return-path: Received: from mail.profihost.ag ([85.158.179.208]:60026 "EHLO mail.profihost.ag" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754892Ab2FRJ3D (ORCPT ); Mon, 18 Jun 2012 05:29:03 -0400 Sender: netdev-owner@vger.kernel.org List-ID: Hello list, i've discovered very unstable 10GBE performance using recent kernels. I'm using some optimized settings mentioned by intel here (part:Improving Performance): http://downloadmirror.intel.com/5874/eng/README.txt I'm using Intel X520 cards (ixgbe driver version: 3.9.17-NAPI in all tests). I'm measuring the performance with iperf. With 3.0.32 i get constant 9,90 Gbit/s in both directions simultaneously. With 3.4.2 or 3.5.0-rc2 it get sometimes 9,9gbit/s - sometimes 3gbit/s or even sometimes only 1gbit/s throughput. I also tried to change the tcp_congestion_control from cubic to reno, bic and highspeed but no change. I also tried to bisect the issue but there are so many changes in the net kernel part that i'm unable to identify the problem as with some commits i only get 0-300kb/s performance. Any ideas? Greets Stefan