From: Bogdan Costescu Subject: Re: nfs performance: read only/gigE/nolock/1Tb per day Date: Tue, 23 Apr 2002 20:16:06 +0200 (CEST) Sender: nfs-admin@lists.sourceforge.net Message-ID: References: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: nfs@lists.sourceforge.net, Return-path: Received: from mail.iwr.uni-heidelberg.de ([129.206.104.30]) by usw-sf-list1.sourceforge.net with esmtp (Exim 3.31-VA-mm2 #1 (Debian)) id 1704pr-0001vI-00 for ; Tue, 23 Apr 2002 11:16:15 -0700 To: Trond Myklebust In-Reply-To: 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: [ cc-ed to netdev; the discussion was about receiving bursts of ICMP Time Exceeded messages after some large NFS datagrams could not be reassembled; sometimes down/up the interface on the receiver/reassembly side cures it ] On 23 Apr 2002, Trond Myklebust wrote: > > How big are the datagrams compared with the MTU ? With 32K > > datagrams over Ethernet, you're talking about roughly a full Rx > > ring worth of packets (32 is common for the Rx ring size)... > > It has been a while ago (I've since mothballed the machine) but I saw > it on a Pentium 90 with only 8k write sizes. 4k was fine, 8k gave > avalanches. IMHO you can't comletely eliminate hardware related problems: apart from having a slow CPU, some early PCI implementations were buggy (although you don't say if it's PCI or ISA and what's the link speed). > > Does the other side sees these messages ? > > IIRC, yes, and the server was resending the datagrams. From the code, > it looks as if there is no attempt to stop loopback situations > occurring when this goes on: > i.e. resending an ICMP when the server resends a datagram which times > out again appears to be possible. This might be what was happening... That's why I cc-ed netdev. My knowledge above the driver level is close to non-existant... -- Bogdan Costescu IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868 E-mail: Bogdan.Costescu@IWR.Uni-Heidelberg.De _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs