From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753747AbXDJNpE (ORCPT ); Tue, 10 Apr 2007 09:45:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753740AbXDJNpD (ORCPT ); Tue, 10 Apr 2007 09:45:03 -0400 Received: from one.firstfloor.org ([213.235.205.2]:50971 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753109AbXDJNpA (ORCPT ); Tue, 10 Apr 2007 09:45:00 -0400 Date: Tue, 10 Apr 2007 15:44:58 +0200 From: Andi Kleen To: Len Brown Cc: Andi Kleen , Andika Triwidada , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org Subject: Re: CPU offline but power consumption increased? Message-ID: <20070410134458.GA723@one.firstfloor.org> References: <7e0bae390704062123i2dfaf030icd5a710677bc989a@mail.gmail.com> <200704100413.51637.lenb@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200704100413.51637.lenb@kernel.org> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > Speaking for all Intel hardware implemented from pre-history until now, > deep C-states is the best you can do, and there is no special offline > mode to save more power. We don't use deep c states currently; just HLT. Right now it doesn't make much difference because no multi socket servers do deep C states and secondary cores can normally not go deep on their own; but if any of this changes this code would need to be fixed. But cpu off line is really a special case -- maybe it is even possible to do something better on current hardware. > and if the BIOS is implemented properly, the core will be spinning in the > deepest available C-state. Of course, it would probably be more interesting > to simply leave the core on-line and let it go idle... I don't see any BIOS call in play_dead() -Andi