From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Renninger Subject: Re: [RFC PATCH]: ACPI: Automatically online hot-added memory Date: Sat, 20 Mar 2010 21:51:56 +0100 Message-ID: <201003202151.57008.trenn@suse.de> References: <20100309141203.10037.62453.sendpatchset@prarit.bos.redhat.com> <201003191755.35421.trenn@suse.de> <4BA3B315.6080905@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from cantor2.suse.de ([195.135.220.15]:55390 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752592Ab0CTUvw (ORCPT ); Sat, 20 Mar 2010 16:51:52 -0400 In-Reply-To: <4BA3B315.6080905@redhat.com> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Prarit Bhargava Cc: ykzhao , chen gong , Matthew Garrett , "linux-acpi@vger.kernel.org" On Friday 19 March 2010 06:23:33 pm Prarit Bhargava wrote: > > Blocking does not work. > > But I have an idea, whatabout: > > - CPU add rule which only adds a CPU if the corresponding Numa node > > already has onlined memory > > - Memory add rule which adds the memory and also onlines CPUs if the > > Numa node still has offlined CPUs > > > > This has the side effect that you online a CPU which may have been > > offlined on purpose if you hotadd memory on the same node..., a rather > > uncommon case. > > That actually might be more of a problem than you think. It's not > atypical that in the evening a system's components are offlined in order > to save power. This shouldn't be a problem currently, because offlined CPUs drain more power than online ones: http://bugzilla.kernel.org/show_bug.cgi?id=5471 > Maintenance also is scheduled for downtime I don't understand this part. > so when > memory is added to the system we may bring cpus into service > erroneously. I think the "end-user" may not be too happy with this result. ... > > I wanted to post something today, but I couldn't made it. > > Still I more or less could prove that above works and I hopefully can > > show some results on Monday. > > If it works then I'm all for it :) Great. I'll hopefully post some patches in a new thread soon and try to collect all interested people in CC. Thomas