From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 7 May 2002 11:03:28 -0700 From: William Lee Irwin III Subject: Re: [PATCH] rmap 13a Message-ID: <20020507180328.GS15756@holomorphy.com> References: <20020507183741.A25245@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Description: brief message Content-Disposition: inline In-Reply-To: <20020507183741.A25245@infradead.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Hellwig Cc: Rik van Riel , Samuel Ortiz , linux-mm@kvack.org List-ID: On Mon, May 06, 2002 at 11:17:26PM -0300, Rik van Riel wrote: >> rmap 13a: >> - NUMA changes for page_address (Samuel Ortiz) On Tue, May 07, 2002 at 06:37:41PM +0100, Christoph Hellwig wrote: > I don't think the changes makes sense. If calculating page_address is > complicated and slow enough to place it out-of-lin using page->virtual > is much better. On Tue, May 07, 2002 at 06:37:41PM +0100, Christoph Hellwig wrote: > I'd suggest backing this patch out and instead always maintain page->virtual > for discontigmem. While at this as a little cleanup you might want to > define WANT_PAGE_VIRTUAL based on CONFIG_HIGHMEM || CONFIG_DISCONTIGMEM > at the top of mm.h instead of cluttering it up. > Christoph This is a time/space tradeoff that may not necessarily be the case for all discontiguous memory architectures. It seems to be so for SGI's machines, though. I advocated this as a matter of generality, despite not having a specific example of a machine that wants it. It's not difficult to produce examples of small-memory architectures with discontiguous memory, though SGI's discontigmem implementation does not appear to be in widespread use for them. Cheers, Bill -- 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/