From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 7 Nov 2006 18:08:44 -0800 (PST) From: Christoph Lameter Subject: Re: Page allocator: Single Zone optimizations In-Reply-To: <20061108092957.d9f7fc74.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <454A2CE5.6080003@shadowen.org> <20061108092957.d9f7fc74.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Mel Gorman , apw@shadowen.org, akpm@osdl.org, nickpiggin@yahoo.com.au, linux-mm@kvack.org, a.p.zijlstra@chello.nl List-ID: On Wed, 8 Nov 2006, KAMEZAWA Hiroyuki wrote: > In these days, I've struggled with crashdump from a user to investigate the reason > of oom-kill. At last, the reason was most of 2G bytes ZONE_DMA pages were > mlocked(). Sigh.... > I wonder we can use migration of MOVABLE pages for zone balancing in future. > (maybe complicated but...) If we run out of ZONE_DMA memory in the page allocator then scan through the LRU of ZONE_DMA for pages, call isolate_lru_page() for each page that you find worthy of moving (all mlocked pages f.e.) and when you have collected a sufficient quantity call migrate_pages() to get all that are movable out of ZONE_DMA. Note though that any writeback of the migrated pages to devices that require pages <2G will then allocate a bounce buffer for the page. Seems that you found another reason why it would be useful to get rid of ZONE_DMA entirely. -- 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