From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nick Piggin Subject: Re: [PATCH] knfsd: Stop NFSD writes from being broken into lots of little writes to filesystem. Date: Tue, 13 Feb 2007 17:11:19 +1100 Message-ID: <45D15687.5080505@yahoo.com.au> References: <20070213170049.3488.patches@notabene> <1070213060131.3560@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Andrew Morton , nfs@lists.sourceforge.net, linux-kernel@vger.kernel.org, "Vladimir V \".\" Saveliev" , Norman Weathers To: NeilBrown Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list2-new.sourceforge.net with esmtp (Exim 4.43) id 1HGqtD-0000ut-LO for nfs@lists.sourceforge.net; Mon, 12 Feb 2007 22:11:43 -0800 Received: from smtp103.mail.mud.yahoo.com ([209.191.85.213]) by mail.sourceforge.net with smtp (Exim 4.44) id 1HGqtE-0004Hz-Rn for nfs@lists.sourceforge.net; Mon, 12 Feb 2007 22:11:45 -0800 In-Reply-To: <1070213060131.3560@suse.de> List-Id: "Discussion of NFS under Linux development, interoperability, and testing." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfs-bounces@lists.sourceforge.net Errors-To: nfs-bounces@lists.sourceforge.net NeilBrown wrote: > Another nfsd patch for 2.6.21... > > ### Comments for Changeset > > When NFSD receives a write request, the data is typically in a number > of 1448 byte segments and writev is used to collect them together. > > Unfortunately, generic_file_buffered_write passes these to the filesystem > one at a time, so an e.g. 32K over-write becomes a series of partial-page > writes to each page, causing the filesystem to have to pre-read those > pages - wasted effort. > > generic_file_buffered_write handles one segment of the vector at a > time as it has to pre-fault in each segment to avoid deadlocks. When > writing from kernel-space (and nfsd does) this is not an issue, so > generic_file_buffered_write does not need to break and iovec from nfsd > into little pieces. > > This patch avoids the splitting when get_fs is KERNEL_DS as it is > from NFSd. > > This issue was introduced by commit 6527c2bdf1f833cc18e8f42bd97973d583e4aa83 > > Cc: Nick Piggin FWIW, you can put Acked-by: me there if you'd like. Thanks, Nick -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751123AbXBMGLk (ORCPT ); Tue, 13 Feb 2007 01:11:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751126AbXBMGLk (ORCPT ); Tue, 13 Feb 2007 01:11:40 -0500 Received: from smtp103.mail.mud.yahoo.com ([209.191.85.213]:44132 "HELO smtp103.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751123AbXBMGLj (ORCPT ); Tue, 13 Feb 2007 01:11:39 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=FVefIeVvfEfVImTpB83+sMCBVM0Ihhli/TK249aRDbIRJHTxynUCtEA6Hlrx+11dNPYNlKiH8hJdnAKmFs+J/6LoK2ukZr+EqD4d/m5edDyx73V0P81HiRm8cmabGxylTVt10G+m623oRqVw22y1xbsG3sw1P8ibtQY2P4GPL1I= ; X-YMail-OSG: qJt11s8VM1mlDWLPvBNuzgYzZk6ycgij11IHDVBnP4s85EuwkX22PLDPgRESPhYKJbEzOMjt87HkgqjdyXCfGAbq7a9gK8Fs.HjRC8wzaF49JerZtsvciPCuez4nx0XVrxcaCVhbuJf8Eug- Message-ID: <45D15687.5080505@yahoo.com.au> Date: Tue, 13 Feb 2007 17:11:19 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: NeilBrown CC: Andrew Morton , nfs@lists.sourceforge.net, linux-kernel@vger.kernel.org, Norman Weathers , "Vladimir V \".\" Saveliev" Subject: Re: [PATCH] knfsd: Stop NFSD writes from being broken into lots of little writes to filesystem. References: <20070213170049.3488.patches@notabene> <1070213060131.3560@suse.de> In-Reply-To: <1070213060131.3560@suse.de> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org NeilBrown wrote: > Another nfsd patch for 2.6.21... > > ### Comments for Changeset > > When NFSD receives a write request, the data is typically in a number > of 1448 byte segments and writev is used to collect them together. > > Unfortunately, generic_file_buffered_write passes these to the filesystem > one at a time, so an e.g. 32K over-write becomes a series of partial-page > writes to each page, causing the filesystem to have to pre-read those > pages - wasted effort. > > generic_file_buffered_write handles one segment of the vector at a > time as it has to pre-fault in each segment to avoid deadlocks. When > writing from kernel-space (and nfsd does) this is not an issue, so > generic_file_buffered_write does not need to break and iovec from nfsd > into little pieces. > > This patch avoids the splitting when get_fs is KERNEL_DS as it is > from NFSd. > > This issue was introduced by commit 6527c2bdf1f833cc18e8f42bd97973d583e4aa83 > > Cc: Nick Piggin FWIW, you can put Acked-by: me there if you'd like. Thanks, Nick -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com