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Date: Mon, 24 May 2010 09:03:53 +0800 From: "Guo, Chaohong" <chaohong.guo@...el.com> To: Lee Schermerhorn <Lee.Schermerhorn@...com>, minskey guo <chaohong_guo@...ux.intel.com> CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>, Stephen Rothwell <sfr@...b.auug.org.au>, Andrew Morton <akpm@...ux-foundation.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "prarit@...hat.com" <prarit@...hat.com>, "Kleen, Andi" <andi.kleen@...el.com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Tejun Heo <tj@...nel.org>, "stable@...nel.org" <stable@...nel.org> Subject: RE: [PATCH] online CPU before memory failed in pcpu_alloc_pages() >> >> >> >> >> >> @@ -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 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. Yeah, that's what I am looking for. 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@...ck.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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