From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lgeamrelo04.lge.com (lgeamrelo04.lge.com [156.147.1.127]) by ozlabs.org (Postfix) with ESMTP id 31B572C00AA for ; Mon, 10 Feb 2014 12:09:32 +1100 (EST) Date: Mon, 10 Feb 2014 10:09:36 +0900 From: Joonsoo Kim To: David Rientjes Subject: Re: [RFC PATCH 2/3] topology: support node_numa_mem() for determining the fallback node Message-ID: <20140210010936.GA12574@lge.com> References: <20140206020757.GC5433@linux.vnet.ibm.com> <1391674026-20092-1-git-send-email-iamjoonsoo.kim@lge.com> <1391674026-20092-2-git-send-email-iamjoonsoo.kim@lge.com> <20140207054819.GC28952@lge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Cc: Han Pingtian , Nishanth Aravamudan , Pekka Enberg , Linux Memory Management List , Paul Mackerras , Anton Blanchard , Matt Mackall , Christoph Lameter , linuxppc-dev@lists.ozlabs.org, Wanpeng Li List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sat, Feb 08, 2014 at 01:57:39AM -0800, David Rientjes wrote: > On Fri, 7 Feb 2014, Joonsoo Kim wrote: > > > > It seems like a better approach would be to do this when a node is brought > > > online and determine the fallback node based not on the zonelists as you > > > do here but rather on locality (such as through a SLIT if provided, see > > > node_distance()). > > > > Hmm... > > I guess that zonelist is base on locality. Zonelist is generated using > > node_distance(), so I think that it reflects locality. But, I'm not expert > > on NUMA, so please let me know what I am missing here :) > > > > The zonelist is, yes, but I'm talking about memoryless and cpuless nodes. > If your solution is going to become the generic kernel API that determines > what node has local memory for a particular node, then it will have to > support all definitions of node. That includes nodes that consist solely > of I/O, chipsets, networking, or storage devices. These nodes may not > have memory or cpus, so doing it as part of onlining cpus isn't going to > be generic enough. You want a node_to_mem_node() API for all possible > node types (the possible node types listed above are straight from the > ACPI spec). For 99% of people, node_to_mem_node(X) is always going to be > X and we can optimize for that, but any solution that relies on cpu online > is probably shortsighted right now. > > I think it would be much better to do this as a part of setting a node to > be online. Okay. I got your point. I will change it to rely on node online if this patch is really needed. Thanks!