From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id B20EB6B01B1 for ; Sun, 23 May 2010 21:04:39 -0400 (EDT) From: "Guo, Chaohong" Date: Mon, 24 May 2010 09:03:53 +0800 Subject: RE: [PATCH] online CPU before memory failed in pcpu_alloc_pages() Message-ID: 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> <4BF642BB.2020402@linux.intel.com> <20100521173940.8f130205.kamezawa.hiroyu@jp.fujitsu.com> <4BF64E79.4010401@linux.intel.com> <1274448107.9131.87.camel@useless.americas.hpqcorp.net> In-Reply-To: <1274448107.9131.87.camel@useless.americas.hpqcorp.net> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org To: Lee Schermerhorn , minskey guo Cc: KAMEZAWA Hiroyuki , Stephen Rothwell , Andrew Morton , "linux-mm@kvack.org" , "prarit@redhat.com" , "Kleen, Andi" , "linux-kernel@vger.kernel.org" , Tejun Heo , "stable@kernel.org" List-ID: >> >> >> >> >> >> @@ -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) =3D local_memory_node(cpu_to_node(cpu)); >> >> +#endif >> >> Look at the above code, int __build_all_zonelists(), cpu_to_mem(cpu) >> is set only when cpu is onlined. Suppose that a node with local memory, >> all memory segments are onlined first, and then, cpus within that node >> are onlined one by one, in this case, where does the cpu_to_mem(cpu) >> for the last cpu get its value ? > >Minskey: > >As I mentioned to Kame-san, x86 does not define >CONFIG_HAVE_MEMORYLESS_NODES, so this code is not compiled for that >arch. If x86 did support memoryless nodes--i.e., did not hide them and >reassign the cpus to other nodes, as is the case for ia64--then we could >have on-line cpus associated with memoryless nodes. The code above is >in __build_all_zonelists() so that in the case where we add memory to a >previously memoryless node, we re-evaluate the "local memory node" for >all online cpus. > >For cpu hotplug--again, if x86 supports memoryless nodes--we'll need to >add a similar chunk to the path where we set up the cpu_to_node map for >a hotplugged cpu. See, for example, the call to set_numa_mem() in >smp_callin() in arch/ia64/kernel/smpboot.c.=20 Yeah, that's what I am looking for.=20 But currently, I don't >think you can use the numa_mem_id()/cpu_to_mem() interfaces for your >purpose. I suppose you could change page_alloc.c to compile >local_memory_node() #if defined(CONFIG_HAVE_MEMORYLESS_NODES) || >defined >(CPU_HOTPLUG) and use that function to find the nearest memory. It >should return a valid node after zonelists have been rebuilt. > >Does that make sense? Yes, besides, I need to find a place in hotplug path to call set_numa_mem(= ) just as you mentioned for ia64 platform. Is my understanding right ? Thanks, -minskey > >Lee >> >> >> > >> > So, cpu_to_node(cpu) for possible cpus will have NUMA_NO_NODE(-1) >> > or the number of the nearest node. >> > >> > IIUC, if SRAT is not broken, all pxm has its own node_id. >> >> Thank you very much for the info, I have been thinking why node_id >> is (-1) in some cases. >> >> >> -minskey >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: email@kvack.org -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org