Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754522AbbDIWhR (ORCPT ); Thu, 9 Apr 2015 18:37:17 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:42982 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753284AbbDIWhO (ORCPT ); Thu, 9 Apr 2015 18:37:14 -0400 Date: Thu, 9 Apr 2015 15:37:09 -0700 From: Nishanth Aravamudan To: Brice Goglin Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Srikar Dronamraju , Boqun Feng , Anshuman Khandual , linuxppc-dev@lists.ozlabs.org, Benjamin Herrenschmidt , Anton Blanchard Subject: Re: Topology updates and NUMA-level sched domains Message-ID: <20150409223709.GF53918@linux.vnet.ibm.com> References: <20150406214558.GA38501@linux.vnet.ibm.com> <20150407102147.GJ23123@twins.programming.kicks-ass.net> <20150407171410.GA62529@linux.vnet.ibm.com> <20150407194129.GT23123@twins.programming.kicks-ass.net> <552503A1.3050502@inria.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <552503A1.3050502@inria.fr> X-Operating-System: Linux 3.13.0-40-generic (x86_64) User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15040922-0021-0000-0000-000009B9CD42 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 898 Lines: 23 On 08.04.2015 [12:32:01 +0200], Brice Goglin wrote: > Le 07/04/2015 21:41, Peter Zijlstra a ?crit : > > No, that's very much not the same. Even if it were dealing with hotplug > > it would still assume the cpu to return to the same node. > > > > But mostly people do not even bother to handle hotplug. > > > > You said userspace assumes the cpu<->node relation is a boot-time fixed > one, and hotplug breaks this. How do you expect userspace to handle > hotplug? Is there a convenient way to be notified when a CPU (or memory) > is unplugged? There is some mention of "User Space Notification" in cpu-hotplug.txt, but no idea if it's current. -Nish -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/