Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932982Ab0BPPA1 (ORCPT ); Tue, 16 Feb 2010 10:00:27 -0500 Received: from gir.skynet.ie ([193.1.99.77]:36390 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932963Ab0BPO77 (ORCPT ); Tue, 16 Feb 2010 09:59:59 -0500 Date: Tue, 16 Feb 2010 14:59:44 +0000 From: Mel Gorman To: Christoph Lameter Cc: KOSAKI Motohiro , Andrea Arcangeli , Adam Litke , Avi Kivity , David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 05/12] Memory compaction core Message-ID: <20100216145943.GA997@csn.ul.ie> References: <1265976059-7459-1-git-send-email-mel@csn.ul.ie> <1265976059-7459-6-git-send-email-mel@csn.ul.ie> <20100216170014.7309.A69D9226@jp.fujitsu.com> <20100216084800.GC26086@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1878 Lines: 46 On Tue, Feb 16, 2010 at 08:55:46AM -0600, Christoph Lameter wrote: > On Tue, 16 Feb 2010, Mel Gorman wrote: > > > Because how do I tell in advance that the data I am migrating from DMA can > > be safely relocated to the NORMAL zone? We don't save GFP flags. Granted, > > for DMA, that will not matter as pages that must be in DMA will also not by > > migratable. However, buffer pages should not get relocated to HIGHMEM for > > example which is more likely to happen. It could be special cased but > > I'm not aware of ZONE_DMA-related pressure problems that would make this > > worthwhile and if so, it should be handled as a separate patch series. > > Oh there are numerous ZONE_DMA pressure issues if you have ancient / > screwed up hardware that can only operate on DMA or DMA32 memory. > I've never ran into the issue. I was under the impression that the only device that might care these days are floopy disks. > Moving page cache pages out of the DMA zone would be good. A > write request will cause the page to bounce back to the DMA zone if the > device requires the page there. > > But I also think that the patchset should be as simple as possible so that > it can be merged soon. > Agreed. > > Ah, it was 2009 when I last kicked this around heavily :) I'll update > > it. > > But it was authored in 2009. May be important if patent or other > copyright claims arise. 2009-2010? > 2007-2010 in that case because 2007 was when I first prototyped this. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/