From mboxrd@z Thu Jan 1 00:00:00 1970 Date: 18 May 2005 18:53:58 +0200 Date: Wed, 18 May 2005 18:53:58 +0200 From: Andi Kleen Subject: Re: [patch 2/4] add x86-64 Kconfig options for sparsemem Message-ID: <20050518165358.GF88141@muc.de> References: <200505181643.j4IGhm7S026977@snoqualmie.dp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200505181643.j4IGhm7S026977@snoqualmie.dp.intel.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Matt Tolentino Cc: akpm@osdl.org, apw@shadowen.org, haveblue@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Wed, May 18, 2005 at 09:43:48AM -0700, Matt Tolentino wrote: > >From: Andi Kleen > >On Wed, May 18, 2005 at 08:24:41AM -0700, Matt Tolentino wrote: > >> > >> Add the requisite arch specific Kconfig options to enable > >> the use of the sparsemem implementation for NUMA kernels > >> on x86-64. > > > >How much did you test sparsemem on x86-64 NUMA ? > > > >There are various cases that probably need to be checked, > >AMD with SRAT, AMD without SRAT, AMD with more than 4GB RAM, > >Summit(?), NUMA EMULATION etc. > > > >If all that works I would have no problem with removing the > >old code. > > As my disclaimer said, this has only been tested using > the NUMA EMULATION config option. That's a big part of > the reason for sending this out - to get further testing > on real x86-64 NUMA systems, but without breaking the > current discontigmem code. Hmm, I would have assumed IBM tested it, since Dave Hansen signed off - they have a range of Opteron machines. If not I can test it on a few boxes later. A single box is not enough, there are various special cases. e.g. one area I've been fighting with is that with SRAT and 3+GB memory the nodes don't span the PCI memory hole anymore, and when there is a virt_to_page() or similar for these addresses things go wrong because they do a uninitialized hash table lookup. If it's not that hard and doesn't cause code bloat I would recommend to harden sparsemem against this case, at least for upto 4GB. -Andi -- 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: aart@kvack.org