From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Mitchell Subject: Re: mmap() and NFS server performance Date: Mon, 16 Dec 2002 14:04:01 -0600 Sender: nfs-admin@lists.sourceforge.net Message-ID: <3DFE31B1.40306@geodev.com> References: <3DFA4C9A.50101@geodev.com> <3DFDE455.1000004@geodev.com> <15869.59466.167433.194706@charged.uio.no> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Cc: nfs@lists.sourceforge.net Return-path: Received: from gateway2.geodev.com ([64.45.165.170] ident=[QNCnXdb1HP3jtZrPFNSx1xfCfzCaYAob]) by sc8-sf-list1.sourceforge.net with esmtp (Exim 3.31-VA-mm2 #1 (Debian)) id 18O1X1-0000kK-00 for ; Mon, 16 Dec 2002 12:08:03 -0800 To: trond.myklebust@fys.uio.no Errors-To: nfs-admin@lists.sourceforge.net List-Help: List-Post: List-Subscribe: , List-Id: Discussion of NFS under Linux development, interoperability, and testing. List-Unsubscribe: , List-Archive: Trond Myklebust wrote: >>>>>>" " == Matthew Mitchell writes: >>>>> > > > 1) What would you like to see, tcpdump/snoop wise, to verify > > this? > > nfsstat on the client should normally tell you how often you are > seeing RPC retransmits. Ran the program again. In 20 minutes, around 20k total client RPC requests, with an assortment of retrans, time, and badxid errors. I am starting to believe that there is a problem using UDP, and that it alone might be enough to explain the slowness. It seems to have negotiated an 8k transfer size. Reasonable? > > 2) Could UDP service really be causing this order of magnitude > > slowdown? > > Certainly: retransmissions follow an *exponential* backoff rule. For > that reason, it doesn't take a very high percentage of retransmissions > before you see a large impact. Seems to be borne out by the evidence. > > 3) Is TCP server code "ready enough" for production use? In > > our case we > > don't mind some occasional bugs, but it needs to be able to > > stay working under reasonable load for a day or so at a time > > for us to get anything done ("Stale NFS file handle" is a > > scourge...). > > That is more of a question for Neil Brown, but I personally don't have > any particularly bad experiences to report. Any particularly *good* ones? :) Would you recommend the 2.4.20 set, or some additional patches? I will probably install the new kernel when we get a little downtime later this week (and then I will promptly go on vacation; hope it stays up! ha!). Thanks for the suggestions and assistance. I'll report back with TCP info for anyone who is interested. -- Matthew Mitchell Systems Programmer/Administrator matthew@geodev.com Geophysical Development Corporation phone 713 782 1234 1 Riverway Suite 2100, Houston, TX 77056 fax 713 782 1829 ------------------------------------------------------- This sf.net email is sponsored by: With Great Power, Comes Great Responsibility Learn to use your power at OSDN's High Performance Computing Channel http://hpc.devchannel.org/ _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs