From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eliezer Tamir Subject: Re: [PATCH 7/8] sched, net: Fixup busy_loop_us_clock() Date: Fri, 29 Nov 2013 15:52:10 +0200 Message-ID: <52989C0A.7000309@linux.intel.com> References: <20131126155743.116756708@infradead.org> <20131126160815.293633156@infradead.org> <529773FC.6020707@linux.intel.com> <20131128174001.GH10022@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mga02.intel.com ([134.134.136.20]:45620 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754666Ab3K2NwQ (ORCPT ); Fri, 29 Nov 2013 08:52:16 -0500 In-Reply-To: <20131128174001.GH10022@twins.programming.kicks-ass.net> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Peter Zijlstra Cc: Arjan van de Ven , lenb@kernel.org, rjw@rjwysocki.net, David Miller , rui.zhang@intel.com, jacob.jun.pan@linux.intel.com, Mike Galbraith , Ingo Molnar , hpa@zytor.com, Thomas Gleixner , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org On 28/11/2013 19:40, Peter Zijlstra wrote: > On Thu, Nov 28, 2013 at 06:49:00PM +0200, Eliezer Tamir wrote: >> I have tested this patch and I see a performance regression of about >> 1.5%. > > Cute, can you qualify your metric? Since this is a poll loop the only > metric that would be interesting is the response latency. Is that what's > increased by 1.5%? Also, what's the standard deviation of your result? Sorry, I should have been more specific. I use netperf tcp_rr, with all settings except the time (30s) on their defaults. The setup is exactly the same as in the commit message of the original patch set. I get 91.5 KRR/s vs. 90.0 KRR/s. Unfortunately you need two machines, both of which need NICs that have driver support for busy poll. currently AFAIK bnx2x, ixgbe, mlx4 and myri10ge are the only ones, but it's not that hard to add to most NAPI based drivers. I will try to test your latest patches and hopefully also get some perf numbers on Sunday. Thanks, Eliezer