From mboxrd@z Thu Jan 1 00:00:00 1970 From: Len Brown Subject: Re: [PATCH 4/5] ACPI: Do cpufreq clamping for throttling per package v2 Date: Mon, 13 Feb 2012 18:30:33 -0500 Message-ID: <4F399D19.9090904@kernel.org> References: <1328545032-21373-1-git-send-email-andi@firstfloor.org> <1328545032-21373-5-git-send-email-andi@firstfloor.org> <20120206163106.GB32061@srcf.ucam.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-qw0-f46.google.com ([209.85.216.46]:51864 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755925Ab2BMXag (ORCPT ); Mon, 13 Feb 2012 18:30:36 -0500 In-Reply-To: <20120206163106.GB32061@srcf.ucam.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Matthew Garrett Cc: Andi Kleen , linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, Andi Kleen On 02/06/2012 11:31 AM, Matthew Garrett wrote: > On Mon, Feb 06, 2012 at 08:17:11AM -0800, Andi Kleen wrote: >> +#define reduction_pctg(cpu) \ >> + per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu)) > > I don't like using percentages here - we end up with the potential for > several percentages to end up mapping to the same P state. Does it matter? > I've sent a > patch that replaces the percentage code with just stepping through P > states instead. But otherwise, yes, this seems sensible. An open > question is whether we should be doing the same on _PPC notifications. > There's some vague evidence that Windows does. If you stepped by P-states, then you behave entirely differently on a machine with many P-states vs a machine with few P-states. There is code floating about that exposes every 100 MHz step on SNB and later as a P-state -- you can have quite a few... thanks, -Len Brown, Intel Open Source Technology Center