Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933524Ab3CUPpY (ORCPT ); Thu, 21 Mar 2013 11:45:24 -0400 Received: from mga01.intel.com ([192.55.52.88]:51128 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932453Ab3CUPpX (ORCPT ); Thu, 21 Mar 2013 11:45:23 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,887,1355126400"; d="scan'208";a="310036042" Message-ID: <514B2B03.4030301@linux.intel.com> Date: Thu, 21 Mar 2013 08:45:07 -0700 From: Arjan van de Ven User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130307 Thunderbird/17.0.4 MIME-Version: 1.0 To: Steven Rostedt CC: paulmck@linux.vnet.ibm.com, Frederic Weisbecker , Rob Landley , linux-kernel@vger.kernel.org, josh@joshtriplett.org, zhong@linux.vnet.ibm.com, khilman@linaro.org, geoff@infradead.org, tglx@linutronix.de Subject: Re: [PATCH] nohz1: Documentation References: <1363636794.15703.32@driftwood> <20130318222548.GG3656@linux.vnet.ibm.com> <1363822338.6345.33.camel@gandalf.local.home> <20130320235545.GL3637@linux.vnet.ibm.com> <1363825631.6345.45.camel@gandalf.local.home> In-Reply-To: <1363825631.6345.45.camel@gandalf.local.home> 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 Content-Length: 1029 Lines: 24 On 3/20/2013 5:27 PM, Steven Rostedt wrote: > I'm not sure I would recommend idle=poll either. It would certainly > work, but it goes to the other extreme. You think NO_HZ=n drains a > battery? Try idle=poll. do not ever use idle=poll on anything production.. really bad idea. if you temporary cannot cope with the latency, you can use the PMQOS system to limit (including going all the way to idle=poll). but using idle=poll completely is very nasty for the hardware. In addition we should document that idle=poll will cost you peak performance, possibly quite a bit. the same is true for the kernel paramter to some extend; it's there to work around broken bioses/hardware/etc; if you have a latency/runtime requirement, it's much better to use PMQOS for this from userspace. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/