From: Trond Myklebust Subject: Re: can anyone explain this state? Date: Wed, 17 Aug 2005 08:02:54 -0400 Message-ID: <1124280174.23245.4.camel@lade.trondhjem.org> References: Mime-Version: 1.0 Content-Type: text/plain Cc: nfs@lists.sourceforge.net Return-path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.91] helo=mail.sourceforge.net) by sc8-sf-list2.sourceforge.net with esmtp (Exim 4.30) id 1E5Mde-0006v4-OZ for nfs@lists.sourceforge.net; Wed, 17 Aug 2005 05:03:22 -0700 Received: from pat.uio.no ([129.240.130.16] ident=7411) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1E5Mde-0006I1-CH for nfs@lists.sourceforge.net; Wed, 17 Aug 2005 05:03:22 -0700 To: Michael In-Reply-To: Sender: nfs-admin@lists.sourceforge.net Errors-To: nfs-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: Discussion of NFS under Linux development, interoperability, and testing. List-Post: List-Help: List-Subscribe: , List-Archive: on den 17.08.2005 Klokka 19:13 (+0800) skreiv Michael: > Hi, > > These day, I observed a strange thing when I copy a 100MB file from > nfs server, both client and server is running redhat 9.0 with kernel > 2.4.20-8: > > $ sudo mount -o > rw,bg,vers=3,tcp,timeo=600,rsize=1024,wsize=1024,hard,intr,ac > server1:/home/test filetest > $ time cp ./filetest/new100m /tmp/o100m > > real 1m6.575s > user 0m0.040s > sys 0m1.430s > $ time cp ./filetest/new100m /tmp/o100m > > real 0m4.964s =================> it is so different comparing > with above time!! > user 0m0.030s > sys 0m0.570s This is done using synchronous writes. Each write will wait for the server to commit it to disk. > $ sudo umount filetest > $ sudo mount -o > rw,bg,vers=3,tcp,timeo=600,rsize=102400,wsize=102400,hard,intr,ac > server1:/home/test filetest > $ time cp ./filetest/new100m /tmp/o100m > > real 0m9.075s > user 0m0.020s > sys 0m0.470s > $ time cp ./filetest/new100m /tmp/o100m > > real 0m7.501s ==================>only different in 2 seconds! > why not less than 4.9 seconds? > user 0m0.000s > sys 0m0.520s This is done using asynchronous writes. Much faster, and no need (on NFSv3) to wait for the disk before sending the next request. The reason is that on 2.4 kernels (and early 2.6 kernels) we could only do synchronous writes when you set wsize < PAGE_SIZE. Cheers, Trond ------------------------------------------------------- SF.Net email is Sponsored by the Better Software Conference & EXPO September 19-22, 2005 * San Francisco, CA * Development Lifecycle Practices Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs