From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 00/23] per device dirty throttling -v8 References: <20070803123712.987126000@chello.nl> <20070804063217.GA25069@elte.hu> <20070804070737.GA940@elte.hu> <20070804103347.GA1956@elte.hu> <20070804163733.GA31001@elte.hu> From: Andi Kleen Date: 05 Aug 2007 02:26:53 +0200 In-Reply-To: <20070804163733.GA31001@elte.hu> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Molnar Cc: Linus Torvalds , Peter Zijlstra , linux-mm@kvack.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, akpm@linux-foundation.org, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com, trond.myklebust@fys.uio.no, yingchao.zhou@gmail.com, richard@rsk.demon.co.uk List-ID: Ingo Molnar writes: > > yeah, it's really ugly. But otherwise i've got no real complaint about > ext3 - with the obligatory qualification that "noatime,nodiratime" in > /etc/fstab is a must. This speeds up things very visibly - especially > when lots of files are accessed. It's kind of weird that every Linux > desktop and server is hurt by a noticeable IO performance slowdown due > to the constant atime updates, while there's just two real users of it: > tmpwatch [which can be configured to use ctime so it's not a big issue] > and some backup tools. (Ok, and mail-notify too i guess.) Out of tens of > thousands of applications. So for most file workloads we give Windows a > 20%-30% performance edge, for almost nothing. (for RAM-starved kernel > builds the performance difference between atime and noatime+nodiratime > setups is more on the order of 40%) I always thought the right solution would be to just sync atime only very very lazily. This means if a inode is only dirty because of an atime update put it on a "only write out when there is nothing to do or the memory is really needed" list. -Andi -- 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