From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from rtp-core-2.cisco.com (rtp-core-2.cisco.com [64.102.124.13]) by rtp-dkim-1.cisco.com (8.12.11/8.12.11) with ESMTP id m6UGNWG5011806 for ; Wed, 30 Jul 2008 12:23:32 -0400 Received: from sausatlsmtp1.sciatl.com ([192.133.217.33]) by rtp-core-2.cisco.com (8.13.8/8.13.8) with ESMTP id m6UGNW8d025889 for ; Wed, 30 Jul 2008 16:23:32 GMT Message-ID: <4890957F.6080705@sciatl.com> Date: Wed, 30 Jul 2008 09:23:27 -0700 From: C Michael Sundius MIME-Version: 1.0 Subject: Re: sparcemem or discontig? References: <488F5D5F.9010006@sciatl.com> <1217368281.13228.72.camel@nimitz> <20080730093552.GD1369@brain> In-Reply-To: <20080730093552.GD1369@brain> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andy Whitcroft Cc: Dave Hansen , linux-mm@kvack.org, msundius@sundius.com List-ID: Andy Whitcroft wrote: > On Tue, Jul 29, 2008 at 02:51:21PM -0700, Dave Hansen wrote: > >> On Tue, 2008-07-29 at 11:11 -0700, C Michael Sundius wrote: >> >>> My understanding is that SPARCEMEM is the way of the future, and since >>> I don't really have a NUMA machine, maybe sparcemem is more appropriate, >>> yes? On the other hand I can't find much info about how it works or how >>> to add support for it on an architecture that has here-to-fore not >>> supported that option. >>> >>> Is there anywhere that there is a paper or rfp that describes how the >>> spacemem (or discontig) features work (and/or the differences between >>> then)? >>> >> I think you're talking about sparsemem. :) >> >> My opinion is that NUMA and DISCONTIG are too intertwined to be useful >> apart from the other. I use sparsemem on my non-NUMA 2 CPU laptop since >> it has a 1GB hole. It is *possible* to use DISCONTIG without NUMA, and >> I'm sure people use it this way, but I just personally think it is a bit >> of a pain. >> >> Basically, to add sparsemem support for an architecture, you need a >> header like these: >> >> dave@nimitz:~/lse/linux/2.5/linux-2.6.git$ find | grep sparse | xargs >> grep -c '^.*$' >> ./include/asm-powerpc/sparsemem.h:32 >> ./include/asm-x86/sparsemem.h:34 >> ./include/asm-sh/sparsemem.h:16 >> ./include/asm-mips/sparsemem.h:14 >> ./include/asm-ia64/sparsemem.h:20 >> ./include/asm-s390/sparsemem.h:18 >> ./include/asm-arm/sparsemem.h:10 >> >> These are generally pretty darn small (the largest is 34 lines). You >> also need to tweak some things in your per-arch Kconfig. ARM looks like >> a pretty simple use of sparsemem. You might want to start with what >> they've done. We tried really, really hard to make it easy to add to >> new architectures. >> Pardon my ignorance, but is sparcemem independent of the bootmem allocator? We also use highmem. I noticed that all of our kmap and kmap_atomic code is located in the arch/mips directory. Is the sparcemem also independent of that? should I expect that I will have to make some changes in that... >> Feel free to cc me and Andy (cc'd) on the patches that you come up with. >> I'd be happy to sanity check them for you. If *you* want to document >> the process for the next guy, I'm sure we'd be able to find some spot in >> Documentation/ so the next guy has an easier time. :) >> I'm happy to write a how to for sparcemem. - - - - - Cisco - - - - - This e-mail and any attachments may contain information which is confidential, proprietary, privileged or otherwise protected by law. The information is solely intended for the named addressee (or a person responsible for delivering it to the addressee). If you are not the intended recipient of this message, you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If you have received this e-mail in error, please notify the sender immediately by return e-mail and delete it from your computer. -- 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