From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: Re: [PATCH]new ACPI processor driver to force CPUs idle Date: Fri, 26 Jun 2009 20:49:08 +0100 Message-ID: <20090626194908.GA11492@srcf.ucam.org> References: <20090624041354.GA15936@sli10-desk.sh.intel.com> <1245825558.19816.1861.camel@twins> <20090624074703.GA28458@sli10-desk.sh.intel.com> <1245830585.31755.11.camel@twins> <1246002370.31755.187.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]:47444 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754708AbZFZTtP (ORCPT ); Fri, 26 Jun 2009 15:49:15 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Len Brown Cc: Peter Zijlstra , Shaohua Li , "linux-acpi@vger.kernel.org" , "svaidy@linux.vnet.ibm.com" , "tglx@linutronix.de" , "Pallipadi, Venkatesh" , "andi@firstfloor.org" , Ingo Molnar On Fri, Jun 26, 2009 at 12:46:53PM -0400, Len Brown wrote: > Low Frequency Mode (LFM), aka Pn - the deepest P-state, > is the lowest energy/instruction because it is this highest > frequency available at the lowest voltage that can still > retire instructions. > > That is why it is the first method used -- it returns the > highest power_savings/performance_impact. For a straightforward workload on a dual package system, do you get more performance from two packages running at their lowest P state or from one package at its highest P state and a forced-idle package? Which consumes more power? -- Matthew Garrett | mjg59@srcf.ucam.org