From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx146.postini.com [74.125.245.146]) by kanga.kvack.org (Postfix) with SMTP id 9FD316B005A for ; Wed, 12 Dec 2012 20:18:46 -0500 (EST) Message-ID: <1355361524.5255.9.camel@buesod1.americas.hpqcorp.net> Subject: Re: [PATCH] mm: add node physical memory range to sysfs From: Davidlohr Bueso Date: Wed, 12 Dec 2012 17:18:44 -0800 In-Reply-To: <50C28720.3070205@linux.vnet.ibm.com> References: <1354919696.2523.6.camel@buesod1.americas.hpqcorp.net> <20121207155125.d3117244.akpm@linux-foundation.org> <50C28720.3070205@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Andrew Morton , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, 2012-12-07 at 16:17 -0800, Dave Hansen wrote: > On 12/07/2012 03:51 PM, Andrew Morton wrote: > >> > +static ssize_t node_read_memrange(struct device *dev, > >> > + struct device_attribute *attr, char *buf) > >> > +{ > >> > + int nid = dev->id; > >> > + unsigned long start_pfn = NODE_DATA(nid)->node_start_pfn; > >> > + unsigned long end_pfn = start_pfn + NODE_DATA(nid)->node_spanned_pages; > > hm. Is this correct for all for > > FLATMEM/SPARSEMEM/SPARSEMEM_VMEMMAP/DISCONTIGME/etc? > > It's not _wrong_ per se, but it's not super precise, either. > > The problem is, it's quite valid to have these node_start/spanned ranges > overlap between two or more nodes on some hardware. So, if the desired > purpose is to map nodes to DIMMs, then this can only accomplish this on > _some_ hardware, not all. It would be completely useless for that > purpose for some configurations. > > Seems like the better way to do this would be to expose the DIMMs > themselves in some way, and then map _those_ back to a node. > Good point, and from a DIMM perspective, I agree, and will look into this. However, IMHO, having the range of physical addresses for every node still provides valuable information, from a NUMA point of view. For example, dealing with node related e820 mappings. Andrew, with the documentation patch, would you be wiling to pickup a v2 of this? Thanks, Davidlohr -- 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