From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: Question about way that NICs deliver packets to the kernel Date: Fri, 16 Jul 2010 10:58:46 -0700 Message-ID: <4C409DD6.7060903@hp.com> References: <20100715142418.GA26491@host-a-229.ustcsz.edu.cn> <1279204417.2118.12.camel@achroite.uk.solarflarecom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: Ben Hutchings , romieu@fr.zoreil.com, netdev@vger.kernel.org To: Junchang Wang Return-path: Received: from g4t0015.houston.hp.com ([15.201.24.18]:35675 "EHLO g4t0015.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757297Ab0GPR6t (ORCPT ); Fri, 16 Jul 2010 13:58:49 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Junchang Wang wrote: >>You should also compare the CPU usage. >> >>Ben. >> > > Hi Ben, > I added options -c -C to netperf's command line. Result is as follows: > scheme 1 scheme 2 Imp. > Throughput: 683M 718M 5% > CPU usage: 47.8% 45.6% > > That really surprised me because "top" command showed the CPU usage > was fluctuating between 0.5% and 1.5% rather that between 45% and 50%. Can you tell us a bit more about the system, and which version of netperf you are using? Any chance that the CPU utilization you were looking at in top was just that being charged to netperf the process? "Network processing" does not often get charged to the responsible process, so netperf reports system-wide CPU utilization on the assumption it is the only thing causing the CPUs to be utilized. happy benchmarking, rick jones