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 09:22:20 +0200 Message-ID: <1340176940.4604.801.camel@edumazet-glaptop> References: <4FE0EA33.1000309@profihost.ag> <1340141493.4604.773.camel@edumazet-glaptop> <4FE17522.5050005@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]:40471 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752049Ab2FTHWZ (ORCPT ); Wed, 20 Jun 2012 03:22:25 -0400 Received: by bkcji2 with SMTP id ji2so5869927bkc.19 for ; Wed, 20 Jun 2012 00:22:23 -0700 (PDT) In-Reply-To: <4FE17522.5050005@profihost.ag> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2012-06-20 at 09:00 +0200, Stefan Priebe - Profihost AG wrote: > Am 19.06.2012 23:31, schrieb Eric Dumazet: > > On Tue, 2012-06-19 at 23:08 +0200, Stefan Priebe wrote: > >> i'm testing 10GBE speed with tweo servers. One with 3.5-rc3 nd thoe > >> other one whith RHEL 6 (2.6.32 kernel). > >> > >> I noticed that setting > >> net.ipv4.tcp_timestamps=0 > >> > >> descreased the performance from 9,7 Full Duplex to 3-4Gb/s. > >> > >> Is this bahviour fine? What should / could i tet? > >> > > > > Really, you should provide more input than that, if you really want us > > to help. > > *arg* forgot to add the pastebin links. Sorry. Speed degraded in this > case from 9,88Gbit/s to 2,45Gbit/s. When i turn on timestamps it's > perfect again. Server A has 3.5.0-rc3 and server B has an RHEL6 2.6.32 > kernel. > > Before: > http://pastebin.com/raw.php?i=1gVraWVc > > After: > http://pastebin.com/raw.php?i=NSh8Y29s You have a lot of packet losses add "tc -s -d qdisc" , "ifconfig -a " and "ethtool -S ethX" outputs for both servers