From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 02 Jun 2005 11:42:39 -0700 From: "Martin J. Bligh" Reply-To: "Martin J. Bligh" Subject: Re: Avoiding external fragmentation with a placement policy Version 12 Message-ID: <486490000.1117737759@flay> In-Reply-To: References: <20050531112048.D2511E57A@skynet.csn.ul.ie><429E20B6.2000907@austin.ibm.com> <429E4023.2010308@yahoo.com.au><423970000.1117668514@flay> <429E483D.8010106@yahoo.com.au><434510000.1117670555@flay> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: jschopp@austin.ibm.com, Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@osdl.org List-ID: >> It gets very messy when CIFS requires a large buffer to write back >> to disk in order to free memory ... > > How about just fixing CIFS to submit memory page by page? The network > stack below it supports that just fine and the VFS above it does anyways, > so it doesnt make much sense that CIFS sitting below them uses > larger buffers. Might well be possible, but it's not just CIFS though. I don't see why CIFS needs phys contig memory, but I think some of the drivers do (at least they do at the moment). Large pages and hotplug definitely will. >> There's one example ... we can probably work around it if we try hard >> enough. However, the fundamental question becomes "do we support higher >> order allocs, or not?". If not fine ... but we ought to quit pretending >> we do. If so, then we need to make them more reliable. > > My understanding was that the deal was that order 1 is supposed > to work but somewhat slower, and bigger orders are supposed to work > at boot up time. If that's the decision we come to, I'm OK with it ... but lots of code needs fixing first. However, I don't think that's currently the stated intent, we try pretty hard for up to order 3 in __alloc_pages(). I think we'll have an inherent need for higher orders from what I've seen, and thus we'll have to be capable to some extent of reclaiming mem for those allocs. We should probably put together a list of things that really need it, Joel had a start at one later down this thread. M. -- 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: aart@kvack.org