From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 26 Jan 2007 02:29:55 -0800 From: Andrew Morton Subject: Re: [RFC] Limit the size of the pagecache Message-Id: <20070126022955.f9b6b11f.akpm@osdl.org> In-Reply-To: <20070124141510.7775829c.kamezawa.hiroyu@jp.fujitsu.com> References: <20070124121318.6874f003.kamezawa.hiroyu@jp.fujitsu.com> <20070124141510.7775829c.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Christoph Lameter , aubreylee@gmail.com, svaidy@linux.vnet.ibm.com, nickpiggin@yahoo.com.au, rgetz@blackfin.uclinux.org, Michael.Hennerich@analog.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Wed, 24 Jan 2007 14:15:10 +0900 KAMEZAWA Hiroyuki wrote: > - One for stability > When a customer constructs their detabase(Oracle), the system often goes to oom. > This is because that the system cannot allocate DMA_ZOME memory for 32bit device. > (USB or e100) > Not allowing to use almost all pages as page cache (for temporal use) will be some help. > (Note: construction DB on ext3....so all writes are serialized and the system couldn't > free page cache.) I'm surprised that any reasonable driver has a dependency on ZONE_DMA. Are you sure? Send full oom-killer output, please. > - One for tuing. > Sometimes our cutomer requests us to limit size of page-cache. > > Many cutomers's memory usage reaches 99.x%. (this is very common situation.) > If almost all memories are used by page-cache, and we can think we can free it. > But the customer cannot estimate what amount of page-cache can be freed (without > perfromance regression). > > When a cutomer wants to add a new application, he tunes the system. > But memory usage is always 99%. > page-cache limitation is useful when the customer tunes his system and find > sets of data and page-cache. > (Of course, we can use some other complicated resource management system for this.) > This will allow the users to decide that they need extra memory or not. > > And...some customers want to keep memory Free as much as possible. > 99% memory usage makes insecure them ;) Tell them to do "echo 3 > /proc/sys/vm/drop_caches", then wait three minutes? -- 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