From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 342D86B006A for ; Thu, 14 Jan 2010 13:01:36 -0500 (EST) Date: Thu, 14 Jan 2010 11:01:33 -0700 From: Alex Chiang Subject: Re: SLUB ia64 linux-next crash bisected to 756dee75 Message-ID: <20100114180133.GA4545@ldl.fc.hp.com> References: <20100113002923.GF2985@ldl.fc.hp.com> <20100114005304.GC27766@ldl.fc.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: penberg@cs.helsinki.fi, linux-ia64@vger.kernel.org, linux-mm@kvack.org List-ID: * Christoph Lameter : > On Wed, 13 Jan 2010, Alex Chiang wrote: > > > Firmware puts each cell into a NUMA node, so we should really > > only have 2 nodes, but for some reason, that 3rd node gets > > created too. I haven't inspected the SRAT/SLIT on this machine > > recently, but can do so if you want me to. > > May not have anything to do with the problem we are looking at but memory > setup is screwed up. Funky effects may follow. Actually, I was reminded off-list by my HP colleagues that the memory setup I showed you is common on mid-range and high-end HP ia64 platforms. Lee tells me: The third node is the "interleaved memory" pseudo-node. The firmware always interleaves 512MB of phys address space across the nodes. On these platforms, only interleaved memory is at phys addr 0--needed by firmware, ... All the real NUMA nodes' memory starts at some high phys addr. So, even in "numa mode" [a.k.a. 100% cell local memory], the firmware must create a region of interleaved memory at phys 0. So, we get N+1 nodes. Because node 2 is at phys 0 and contains only 512MB, it is all ZONE_DMA memory. DMA zone is 1st 4G on ia64. Our platforms have been shipping like this for years, so it's not like anything recent has changed. Thanks, /ac -- 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