From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752581Ab2GDNZx (ORCPT ); Wed, 4 Jul 2012 09:25:53 -0400 Received: from mail-gh0-f174.google.com ([209.85.160.174]:34758 "EHLO mail-gh0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751168Ab2GDNZv (ORCPT ); Wed, 4 Jul 2012 09:25:51 -0400 Date: Wed, 4 Jul 2012 15:25:42 +0200 From: Frederic Weisbecker To: Luming Yu Cc: LKML , gilad@benyossef.com, Len Brown , shli@kernel.org, Thomas Gleixner Subject: Re: CPU isolation question again Message-ID: <20120704132539.GD28294@somewhere> References: <20120703112828.GA28294@somewhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 04, 2012 at 08:42:29PM +0800, Luming Yu wrote: > On Tue, Jul 3, 2012 at 7:28 PM, Frederic Weisbecker wrote: > > On Wed, Jun 27, 2012 at 09:22:09PM +0800, Luming Yu wrote: > >> Hi there, > >> > >> I noticed some discussion about CPU isolation which points me to the > >> patch set (https://lkml.org/lkml/2011/8/15/245). I'm currently > >> preparing a RFC-patch-set to automatically pick up a few suitable CPUs > >> to isolate then kick them out of service for a while. We need to > >> balance between thermal & power management And overall system > >> performance during this operation as much as possible. So > >> software-cpu-online-offline interface could not be a good option to > >> me. But to make sure I'm not blindly running on a dead-end path, I'd > >> check with experts here to ensure it makes some sense to isolate CPUs > >> to this level, and the idea also makes some sense, and the most > >> important is it's not implemented yet. > > > > I don't understand what you are trying to do and how exactly. How do you > > plan to do this isolation and how do you want to balance between thermal > > and power? > > My question could be wrong as the question arose several weeks ago > when I came across > drivers/acpi/acpi_paid.c which looks like a real user who need to > request system automatically > pick up a few CPU to get them isolated and deactivated. Later on, I > noticed tglx's cpu hot plug re-work. > I realized we could reuse the interface to do isolation and deactivation work. > > Of cause, to pick up which ones to isolate and deactivate is another problem. > > cc'ed the author and ACPI maintainer of the driver as well as tglx. May be I'm confused because we both have our own definition of isolation. I'm not sure what kind of CPU isolation you're looking for.