From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946888AbdEZDrX (ORCPT ); Thu, 25 May 2017 23:47:23 -0400 Received: from ozlabs.org ([103.22.144.67]:35943 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946858AbdEZDrD (ORCPT ); Thu, 25 May 2017 23:47:03 -0400 From: Michael Ellerman To: Reza Arbab , Balbir Singh Cc: Michael Bringmann , linux-kernel@vger.kernel.org, Paul Mackerras , "Aneesh Kumar K.V" , Bharata B Rao , Shailendra Singh , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Sebastian Andrzej Siewior Subject: Re: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc In-Reply-To: <20170525151011.m4ae4ipxbqsj3mn7@arbab-laptop.localdomain> References: <3bb44d92-b2ff-e197-4bdf-ec6d588d6dab@linux.vnet.ibm.com> <20170523155251.bqwc5mc4jpgzkqlm@arbab-laptop.localdomain> <1c1d70e3-4e45-b035-0e75-1b0f531c111b@linux.vnet.ibm.com> <20170523214922.bns675oqzqj4pkhc@arbab-laptop.localdomain> <87poeya4dt.fsf@concordia.ellerman.id.au> <8e2417d8-d108-2949-40f2-997d53a3f367@linux.vnet.ibm.com> <87a861a25y.fsf@concordia.ellerman.id.au> <20170525151011.m4ae4ipxbqsj3mn7@arbab-laptop.localdomain> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Date: Fri, 26 May 2017 13:46:58 +1000 Message-ID: <87zie08ekt.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Reza Arbab writes: > On Thu, May 25, 2017 at 04:19:53PM +1000, Michael Ellerman wrote: >>The commit message for 3af229f2071f says: >> >> In practice, we never see a system with 256 NUMA nodes, and in fact, we >> do not support node hotplug on power in the first place, so the nodes >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ >> that are online when we come up are the nodes that will be present for >> the lifetime of this kernel. >> >>Is that no longer true? > > I don't know what the reasoning behind that statement was at the time, > but as far as I can tell, the only thing missing for node hotplug now is > Balbir's patchset [1]. He fixes the resource issue which motivated > 3af229f2071f and reverts it. > > With that set, I can instantiate a new numa node just by doing > add_memory(nid, ...) where nid doesn't currently exist. But does that actually happen on any real system? cheers