From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 22 May 2006 10:06:48 +0100 (IST) From: Mel Gorman Subject: Re: [patch 2/2] mm: handle unaligned zones In-Reply-To: <44705291.9070105@yahoo.com.au> Message-ID: References: <4470232B.7040802@yahoo.com.au> <44702358.1090801@yahoo.com.au> <20060521021905.0f73e01a.akpm@osdl.org> <4470417F.2000605@yahoo.com.au> <20060521035906.3a9997b0.akpm@osdl.org> <44705291.9070105@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Andrew Morton , apw@shadowen.org, stable@kernel.org, linux-mm@kvack.org List-ID: On Sun, 21 May 2006, Nick Piggin wrote: > Andrew Morton wrote: > >> How about just throwing the pages away? It sounds like a pretty rare >> problem. > > Well that's what many architectures will end up doing, yes. But on > small or embedded platforms, 4MB - 1 is a whole lot of memory to be > throwing away. > > Also, I'm not sure it is something we can be doing in generic code, > because some architectures apparently have very strange zone setups > (eg. zones from several pages interleaved within a single zone's > ->spanned_pages). I looked through a fair few arches code that sizes zones and I couldn't find this or odd calls to set_page_links(). What arch interleaves pages between zones like this? I am taking you mean that you can have a situation where within one contiguous block of pages you have something like; dddNNNdddNNNddd Where d is a page in ZONE_DMA and N is a page in ZONE_NORMAL. The oddest I've seen is where nodes interleave like on PPC64. There you can have pages for node 0 followed by pages for node 1 followed by node 0 again. But the zone start and end pfns stay in the same place. > So it doesn't sound like a simple matter of trying > to override the zones' intervals. > > -- > SUSE Labs, Novell Inc. > Send instant messages to your online friends http://au.messenger.yahoo.com -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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