From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 24 Nov 2006 20:04:49 +0000 (GMT) From: Mel Gorman Subject: Re: [PATCH 1/11] Add __GFP_MOVABLE flag and update callers In-Reply-To: Message-ID: References: <20061121225022.11710.72178.sendpatchset@skynet.skynet.ie> <20061121225042.11710.15200.sendpatchset@skynet.skynet.ie> <20061123163613.GA25818@skynet.ie> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Linus Torvalds , Mel Gorman , linux-mm@kvack.org, Linux Kernel Mailing List List-ID: On Fri, 24 Nov 2006, Christoph Lameter wrote: > On Thu, 23 Nov 2006, Linus Torvalds wrote: > >> And the assumption would be that if it's MOVABLE, then it's obviously a >> USER allocation (it it can fail much more eagerly - that's really what the >> whole USER bit ends up meaning internally). > > We can probably make several types of kernel allocations movable if there > would be some benefit from it. > Page tables are the major type of allocation that comes to mind. From what I've seen, they are the most common long-lived unmovable and unreclaimable allocation. > Mel already has a problem with mlocked user pages in the movable section. > If this is fixed by using page migration to move the mlocked pages That is the long-term plan. > then we > can likely make addititional classes kernel pages also movable and reduce > the amount of memory that is unmovable. If we have more movable pages then > the defrag can work more efficiently. Indeed, although some sort of placement is still needed to keep these movable allocations together. > Having most pages movable will also > help to make memory unplug a reality. > > So please do not require movable pages to be user allocations. > That is not the intention. It just happens that allocations that are directly accessible by userspace are also the ones that are currently movable. -- 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