From mboxrd@z Thu Jan 1 00:00:00 1970 From: ykzhao Subject: Re: [RFC PATCH]: ACPI: Automatically online hot-added memory Date: Fri, 12 Mar 2010 09:31:07 +0800 Message-ID: <1268357467.3632.55.camel@localhost.localdomain> References: <20100309141203.10037.62453.sendpatchset@prarit.bos.redhat.com> <20100309154243.GA26520@srcf.ucam.org> <4B969305.9070103@redhat.com> <1268186225.3606.25.camel@localhost.localdomain> <4B979E63.1070806@redhat.com> <1268268915.3606.101.camel@localhost.localdomain> <4B985311.8090708@redhat.com> <1268294876.3632.5.camel@localhost.localdomain> <4B98D16D.3090602@redhat.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from mga11.intel.com ([192.55.52.93]:25749 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752452Ab0CLBdM (ORCPT ); Thu, 11 Mar 2010 20:33:12 -0500 In-Reply-To: <4B98D16D.3090602@redhat.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Prarit Bhargava Cc: Matthew Garrett , "linux-acpi@vger.kernel.org" On Thu, 2010-03-11 at 19:18 +0800, Prarit Bhargava wrote: > > ykzhao wrote: > > On Thu, 2010-03-11 at 10:18 +0800, Prarit Bhargava wrote: > > > >>> Yes. The nehalem processor has the integrated memory controller. But it > >>> is not required that the hot-added memory should be onlined before > >>> bringing up CPU. > >>> I do the following memory-hotplug test on one Machine. > >>> a. Before hot plugging memory, four CPUs socket are installed and > >>> all the logical CPU are brought up. (Only one node has the memory) > >>> b. The memory is hot-plugged and then the memory is onlined so that > >>> it can be accessed by the system. > >>> > >>> In the above testing case the CPU is brought up before onlining the > >>> hot-added memory. And the test shows that it can work well. > >>> > >>> > >> That doesn't work when you have multiple nodes AFAICT. The cpus do not > >> come into service because of a lack of memory on the node.... per node > >> allocations will fail. > >> > > > > In the test the system has multiple nodes. The reason is that the cpu > > without memory can turn to other node and allocate the memory. > > > > > >> Just curious, exactly what did you test with? 2.6.33 (or newer)? > >> > > > > I test it on 2.6.32 kernel. > > > > 2.6.32 doesn't work with memory and cpu. > 2.6.33 doesn't work with memory and cpu. I don't test the scenario of both cpu and memory hot-plugging. What I mean is that the 2.6.32 kernel can work if only memory is hot-plugged (The cpu is already brought-up in the boot phase). > > Other patches (which have been posted upstream) are required. > > > I'll try to dig up the patches and you can retest. > > I will try a memory-free cpu add as well to see if that works... but the > performance hit due to the off-node allocations probably doesn't make it > worthwhile. > > > P. > > >