From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: 10GBE performance drop with net.ipv4.tcp_timestamps=0 Date: Wed, 20 Jun 2012 11:16:33 +0200 Message-ID: <1340183793.4604.846.camel@edumazet-glaptop> References: <4FE0EA33.1000309@profihost.ag> <1340141493.4604.773.camel@edumazet-glaptop> <4FE17522.5050005@profihost.ag> <1340176940.4604.801.camel@edumazet-glaptop> <4FE1881B.7030800@profihost.ag> <1340181676.4604.838.camel@edumazet-glaptop> <4FE192A1.6000000@profihost.ag> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Linux Netdev List To: Stefan Priebe - Profihost AG Return-path: Received: from mail-bk0-f46.google.com ([209.85.214.46]:63438 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754645Ab2FTJQi (ORCPT ); Wed, 20 Jun 2012 05:16:38 -0400 Received: by bkcji2 with SMTP id ji2so5940709bkc.19 for ; Wed, 20 Jun 2012 02:16:37 -0700 (PDT) In-Reply-To: <4FE192A1.6000000@profihost.ag> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2012-06-20 at 11:06 +0200, Stefan Priebe - Profihost AG wrote: > Am 20.06.2012 10:41, schrieb Eric Dumazet: > > On Wed, 2012-06-20 at 10:21 +0200, Stefan Priebe - Profihost AG wrote: > >> Am 20.06.2012 09:22, schrieb Eric Dumazet: > > Yes, you already told that in subject line. > > > > single tcp flow ? > I use iperf - i think it uses just a single tcp flow. But i'm not sure. > > > You seem to have a switch or something that drops packets in this case. > > You could try to rate limit to 9Gb/s and see if it is better. > Sadly i can't rate limit to 9Gbit/s on the switch. I was suggesting rate limiting on your linux sender machine, just to verify if its indeed a problem on the path. Its a matter of a "tc qdisc ..." command ;) Or maybe iperf has an option for rate limiting.