From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753977Ab3ACTlk (ORCPT ); Thu, 3 Jan 2013 14:41:40 -0500 Received: from g6t0185.atlanta.hp.com ([15.193.32.62]:15691 "EHLO g6t0185.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753792Ab3ACTlg (ORCPT ); Thu, 3 Jan 2013 14:41:36 -0500 Message-ID: <50E5DEEF.2080009@hp.com> Date: Thu, 03 Jan 2013 11:41:35 -0800 From: Rick Jones User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: Eric Dumazet CC: sedat.dilek@gmail.com, netdev@vger.kernel.org, LKML Subject: Re: [PATCH net-next] softirq: reduce latencies References: <1357219919.21409.24519.camel@edumazet-glaptop> In-Reply-To: <1357219919.21409.24519.camel@edumazet-glaptop> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/03/2013 05:31 AM, Eric Dumazet wrote: > A common network load is to launch ~200 concurrent TCP_RR netperf > sessions like the following > > netperf -H remote_host -t TCP_RR -l 1000 > And then you can launch some netperf asking P99_LATENCY results : > > netperf -H remote_host -t TCP_RR -- -k P99_LATENCY In terms of netperf overhead, once you specify P99_LATENCY, you are already in for the pound of cost but only getting the penny of output (so to speak). While it would clutter the output, one could go ahead and ask for the other latency stats and it won't "cost" anything more: ... -- -k RT_LATENCY,MIN_LATENCY,MAX_LATENCY,P50_LATENCY,P90_LATENCY,P99_LATENCY,MEAN_LATENCY,STDDEV_LATENCY Additional information about how the omni output selectors work can be found at http://www.netperf.org/svn/netperf2/trunk/doc/netperf.html#Omni-Output-Selection happy benchmarking, rick jones BTW - you will likely see some differences between RT_LATENCY, which is calculated from the average transactions per second, and MEAN_LATENCY, which is calculated from the histogram of individual latencies maintained when any of the _LATENCY outputs other than RT_LATENCY is requested. Kudos to the folks at Google who did the extensions to the then-existing histogram code to enable it to be used for more reasonably accurate statistics.