From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267700AbUHTIJ3 (ORCPT ); Fri, 20 Aug 2004 04:09:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267698AbUHTIJB (ORCPT ); Fri, 20 Aug 2004 04:09:01 -0400 Received: from linux2.isphuset.no ([213.236.237.186]:54404 "EHLO gtw.mailserveren.com") by vger.kernel.org with ESMTP id S267620AbUHTIGz (ORCPT ); Fri, 20 Aug 2004 04:06:55 -0400 Subject: SMP cpu deep sleep From: Hans Kristian Rosbach To: linux-kernel@vger.kernel.org Content-Type: text/plain Organization: ISPHuset Nordic AS Message-Id: <1092989207.18275.14.camel@linux.local> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 Date: Fri, 20 Aug 2004 10:06:47 +0200 Content-Transfer-Encoding: 7bit X-Declude-Sender: hk@isphuset.no [195.159.151.115] X-Note: This E-mail was scanned by Declude JunkMail (www.declude.com) for spam. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org While reading through hotplug and speedstep patches I came to think of a feature I think might be useful. In an SMP system there are several cpus, this generates extra heat and power consuption even on idle load. Is there a way to put all cpus but cpu1 into a kind of deep sleep? Cpu1 would have to do all work (including irqs) of course. We have a lot of SMP systems that we host, and they are heavily used ~10 hours of the day, the rest they are mostly idle. They could run on only 1 cpu during lenghty idle periods. If it is possible to put cpus to a deeper sleep than just the simple idle, then the kernel could make use of this. It would be a cool feature. Sincerly Hans K. Rosbach