From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754338Ab0EUIWu (ORCPT ); Fri, 21 May 2010 04:22:50 -0400 Received: from mga12.intel.com ([143.182.124.36]:24143 "EHLO azsmga102.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753133Ab0EUIWr (ORCPT ); Fri, 21 May 2010 04:22:47 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.53,277,1272870000"; d="scan'208";a="279775008" Message-ID: <4BF642BB.2020402@linux.intel.com> Date: Fri, 21 May 2010 16:22:19 +0800 From: minskey guo User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100423 Thunderbird/3.0.4 MIME-Version: 1.0 To: KAMEZAWA Hiroyuki CC: Stephen Rothwell , Andrew Morton , linux-mm@kvack.org, prarit@redhat.com, andi.kleen@intel.com, linux-kernel@vger.kernel.org, minskey guo , Tejun Heo , stable@kernel.org Subject: Re: [PATCH] online CPU before memory failed in pcpu_alloc_pages() References: <1274163442-7081-1-git-send-email-chaohong_guo@linux.intel.com> <20100520134359.fdfb397e.akpm@linux-foundation.org> <20100521105512.0c2cf254.sfr@canb.auug.org.au> <20100521134424.45e0ee36.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100521134424.45e0ee36.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>>> --- a/mm/percpu.c >>>> +++ b/mm/percpu.c >>>> @@ -714,13 +714,29 @@ static int pcpu_alloc_pages(struct pcpu_chunk *chunk, >>> >>> In linux-next, Tejun has gone and moved pcpu_alloc_pages() into the new >>> mm/percpu-vm.c. So either >> >> This has gone into Linus' tree today ... >> > > Hmm, a comment here. > > Recently, Lee Schermerhorn developed > > numa-introduce-numa_mem_id-effective-local-memory-node-id-fix2.patch > > Then, you can use cpu_to_mem() instead of cpu_to_node() to find the > nearest available node. > I don't check cpu_to_mem() is synchronized with NUMA hotplug but > using cpu_to_mem() rather than adding > = > > + if ((nid == -1) || > + !(node_zonelist(nid, GFP_KERNEL)->_zonerefs->zone)) > + nid = numa_node_id(); > + > == > > is better. Yes. I can use cpu_to_mem(). only some little difference during CPU online: 1st cpu within memoryless node gets memory from current node or the node to which the cpu0 belongs, But I have a question about the patch: numa-slab-use-numa_mem_id-for-slab-local-memory-node.patch, @@ -2968,9 +2991,23 @@ static int __build_all_zonelists(void *d ... - for_each_possible_cpu(cpu) + for_each_possible_cpu(cpu) { setup_pageset(&per_cpu(boot_pageset, cpu), 0); ... +#ifdef CONFIG_HAVE_MEMORYLESS_NODES + if (cpu_online(cpu)) + cpu_to_mem(cpu) = local_memory_node(cpu_to_node(cpu)); +#endif Look at the last two lines, suppose that memory is onlined before CPUs, where will cpu_to_mem(cpu) be set to the right nodeid for the last onlined cpu ? Does that CPU always get memory from the node including cpu0 for slab allocator where cpu_to_mem() is used ? thanks, -minskey