From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 30 Aug 2002 17:54:09 -0400 Mime-Version: 1.0 (Apple Message framework v482) Content-Type: text/plain; charset=US-ASCII; format=flowed Subject: Avoiding the highmem mess From: Scott Kaplan Content-Transfer-Encoding: 7bit Message-Id: <0334AD85-BC63-11D6-B00B-000393829FA4@cs.amherst.edu> Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org List-ID: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Folks, As I've mentioned before, I'm trying to do some basic experiments using the Linux VM. Part of doing these experiments will involve reverting the kernel to a more ``classic'' kind of structure: A SEGQ layout where the active pages are managed by a CLOCK algorithm, and the inactive pages are kept in an LRU queue and are marked ``not present'' so that references to them generate a trap. Critically, I don't aim to produce a kernel that will work on non-x86 platforms, let alone NUMA machines or even (at least initially) multiprocessor machines. I want to do some experiments where the heart of the matter lies in testing single-processor management. (Back to basics!) SO! To that end, I'd like to avoid the ZONE_HIGHMEM mess. It seems oddly done, and creates new kinds of contention between pools of pages that I don't want polluting my experiments. (That's not to say that I don't think it's a problem worth solving -- it's just not *the* problem that *I* want to examine just yet.) Is there an easy way to avoid ZONE_HIGHMEM? Is it as easy as avoiding machines that have more than 1 GB of physical memory so that only ZONE_NORMAL is used? I'd be happy to just use ZONE_NORMAL (and ZONE_DMA, which I'm not all that worried about here) and have my experimental code fail to support machines with more than 1 GB. Later I may want to fix that, but I need to start with something simple and comprehensible. Tips? Feedback? Your commentary is greatly appreciated... Scott -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (Darwin) Comment: For info see http://www.gnupg.org iD8DBQE9b+mE8eFdWQtoOmgRAtVbAJ45HVBGz6BsDAEaoMQ8sDPSIIUtlACgjNFX V7wxeT5NNPfS4KDmlqJbsIM= =B0NR -----END PGP SIGNATURE----- -- 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/