From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755851Ab1KGRFK (ORCPT ); Mon, 7 Nov 2011 12:05:10 -0500 Received: from cavan.codon.org.uk ([93.93.128.6]:46921 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752932Ab1KGRFI (ORCPT ); Mon, 7 Nov 2011 12:05:08 -0500 Date: Mon, 7 Nov 2011 17:04:58 +0000 From: Matthew Garrett To: hagar Cc: lkml , Rusty Russell , Srivatsa Vaddagiri , Joel Schopp , Ashok Raj , Heiko Carstens Subject: Re: Fwd: Kernel Power management ?? turning off used devices that are in use. Message-ID: <20111107170458.GA23257@srcf.ucam.org> References: <4EB38A44.5030606@iinet.net.au> <4EB38C99.10809@iinet.net.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4EB38C99.10809@iinet.net.au> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@cavan.codon.org.uk X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 04, 2011 at 02:56:25PM +0800, hagar wrote: > > I have traced this behaviour to the cpu hotplug code. > > I need to be able to either switch off cpu hotpluging - or at least > prevent hotplugging certain cpu's The kernel doesn't automatically hotplug CPUs on idle. Something in your userspace is doing so. I think that Ubuntu's powernap will do so under certain circumstances - try disabling that if you have it. (Which doesn't alter the fact that there appears to be a bug here) -- Matthew Garrett | mjg59@srcf.ucam.org