From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Dangaard Brouer Subject: Re: Loopback performance from kernel 2.6.12 to 2.6.37 Date: Tue, 09 Nov 2010 14:59:19 +0100 Message-ID: <1289311159.17448.9.camel@traveldev.cxnet.dk> References: <1288954189.28003.178.camel@firesoul.comx.local> <1288988955.2665.297.camel@edumazet-laptop> <1289213926.15004.19.camel@firesoul.comx.local> <1289214289.2820.188.camel@edumazet-laptop> <1289228785.2820.203.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: netdev To: Eric Dumazet Return-path: Received: from lanfw001a.cxnet.dk ([87.72.215.196]:50698 "EHLO lanfw001a.cxnet.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751820Ab0KIOHY (ORCPT ); Tue, 9 Nov 2010 09:07:24 -0500 In-Reply-To: <1289228785.2820.203.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 2010-11-08 at 16:06 +0100, Eric Dumazet wrote: ... > > > > > I noticed that the loopback performance has gotten quite bad: > > > > > > > > > > http://www.phoronix.com/scan.php?page=article&item=linux_2612_2637&num=6 > > > CC netdev, if you dont mind. No problem :-) > Their network test is basically : > > netcat -l 9999 >/dev/null & > time dd if=/dev/zero bs=1M count=10000 | netcat 127.0.0.1 9999 Should it not be: netcat -l -p 9999 >/dev/null & When I run the commands "dd | netcat", netcat never finish/exits, I have to press Ctrl-C to stop it. What am I doing wrong? Any tricks? "dd" reports 17.54 sec, and but the "time" measurement cannot be uses as the netcat just hangs/waits for more data... time dd if=/dev/zero bs=1M count=10000 | netcat 127.0.0.1 9999 10000+0 records in 10000+0 records out 10485760000 bytes (10 GB) copied, 17,5419 s, 598 MB/s When I run the commands, I see 261682 context switches per sec... This quick test were on a Core i7 920 using kernel 2.6.32-rc3-net-next-dev-mp2t. -- Jesper Dangaard Brouer ComX Networks A/S