From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751249AbWFSJFZ (ORCPT ); Mon, 19 Jun 2006 05:05:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751254AbWFSJFZ (ORCPT ); Mon, 19 Jun 2006 05:05:25 -0400 Received: from rwcrmhc13.comcast.net ([204.127.192.83]:38111 "EHLO rwcrmhc13.comcast.net") by vger.kernel.org with ESMTP id S1751249AbWFSJFY (ORCPT ); Mon, 19 Jun 2006 05:05:24 -0400 Message-ID: <449668D1.1050200@namesys.com> Date: Mon, 19 Jun 2006 02:05:21 -0700 From: Hans Reiser User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.5) Gecko/20041217 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Nix CC: Andrew Morton , "Vladimir V. Saveliev" , hch@infradead.org, Reiserfs-Dev@namesys.com, Linux-Kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: batched write References: <44736D3E.8090808@namesys.com> <20060524175312.GA3579@zero> <44749E24.40203@namesys.com> <20060608110044.GA5207@suse.de> <1149766000.6336.29.camel@tribesman.namesys.com> <20060608121006.GA8474@infradead.org> <1150322912.6322.129.camel@tribesman.namesys.com> <20060617100458.0be18073.akpm@osdl.org> <4494411B.4010706@namesys.com> <87ac8an21r.fsf@hades.wkstn.nix> In-Reply-To: <87ac8an21r.fsf@hades.wkstn.nix> X-Enigmail-Version: 0.90.1.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Nix wrote: >On 17 Jun 2006, Hans Reiser prattled cheerily: > > >>If the FS is called per page, then it turns out that 3) costs more than >>1) and 2) for sophisticated filesystems. As we develop fancier and >>fancier plugins this will just get more and more true. It decreases CPU >>usage by 2x to use per sys_write calls into reiser4 rather than per page >>calls into reiser4. >> >> > >This seems to me to be something that FUSE filesystems might well like, >too: I know one I'm working on would like to know the real size of the >original write request (so that it can optimize layout appropriately >for things frequently written in large chunks; the assumption being that >if it's written in large chunks it's likely to be read in large chunks >too). > > > Hi Nix, Forgive myn utter ignorance of fuse, but does it currently context switch to user space for every 4k written through VFS?