Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753069Ab2KMV4r (ORCPT ); Tue, 13 Nov 2012 16:56:47 -0500 Received: from mga09.intel.com ([134.134.136.24]:26369 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751447Ab2KMV4q (ORCPT ); Tue, 13 Nov 2012 16:56:46 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.83,768,1352102400"; d="scan'208";a="219201013" Message-ID: <50A2C21D.6070108@linux.intel.com> Date: Tue, 13 Nov 2012 13:56:45 -0800 From: Arjan van de Ven User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:16.0) Gecko/20121026 Thunderbird/16.0.2 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Jacob Pan , Linux PM , LKML , Rafael Wysocki , Len Brown , Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , Zhang Rui , Rob Landley Subject: Re: [PATCH 3/3] PM: Introduce Intel PowerClamp Driver References: <1352757831-5202-1-git-send-email-jacob.jun.pan@linux.intel.com> <1352757831-5202-4-git-send-email-jacob.jun.pan@linux.intel.com> <20121113211602.GA30150@linux.vnet.ibm.com> In-Reply-To: <20121113211602.GA30150@linux.vnet.ibm.com> X-Enigmail-Version: 1.4.5 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 957 Lines: 23 On 11/13/2012 1:16 PM, Paul E. McKenney wrote: > On Mon, Nov 12, 2012 at 02:03:51PM -0800, Jacob Pan wrote: >> Intel PowerClamp driver performs synchronized idle injection across >> all online CPUs. The goal is to maintain a given package level C-state >> ratio. >> >> Compared to other throttling methods already exist in the kernel, >> such as ACPI PAD (taking CPUs offline) and clock modulation, this is often >> more efficient in terms of performance per watt. >> >> Please refer to Documentation/thermal/intel_powerclamp.txt for more details. > > If I read this correctly, this forces a group of CPUs into idle for > about 600 milliseconds at a time. This would indeed delay grace periods, 6ms not 600 -- 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/