From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756521AbZBVOYe (ORCPT ); Sun, 22 Feb 2009 09:24:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753116AbZBVOYG (ORCPT ); Sun, 22 Feb 2009 09:24:06 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:58786 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753065AbZBVOYF (ORCPT ); Sun, 22 Feb 2009 09:24:05 -0500 Date: Sun, 22 Feb 2009 15:23:51 +0100 From: Pavel Machek To: Mike Frysinger Cc: paulmck@linux.vnet.ibm.com, Mathieu Desnoyers , Linus Torvalds , Nick Piggin , Bryan Wu , linux-kernel@vger.kernel.org, ltt-dev@lists.casi.polymtl.ca, uclinux-dist-devel@blackfin.uclinux.org Subject: Re: [ltt-dev] [RFC git tree] Userspace RCU (urcu) for Linux (repost) Message-ID: <20090222142351.GG1586@ucw.cz> References: <20090213155507.GA2838@Krystal> <20090213173352.GB4684@Krystal> <20090213185411.GB7124@Krystal> <20090213193619.GH6854@linux.vnet.ibm.com> <8bd0f97a0902132107r3651ce4rc5bc4e027268e2aa@mail.gmail.com> <20090214052030.GB7194@linux.vnet.ibm.com> <8bd0f97a0902132146t2badab79ue76e0a43d74c95ca@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8bd0f97a0902132146t2badab79ue76e0a43d74c95ca@mail.gmail.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > If Blackfin handles hotplug CPU, that may > > need attention as well, since tasks affinitied to the CPU being removed > > can end up with their affinity set to all CPUs. And there are probably > > other issues. > > no, we dont support hotplugging of CPUs. there is no hardware support > for it, so i think the only thing you'd gain is perhaps power savings > ? not sure it would even work in our case though as the hardware does > not support restarting or shutdown of one core ... they both have to > restart/shutdown. putting one core into a constant idle loop would > save power, but that can already be accomplished by reducing the apps > that go onto a specific core. Well, cpu hotplug is needed for suspend and hibernation... -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html