From owner-freebsd-hackers Sat May 24 02:15:59 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id CAA15484 for hackers-outgoing; Sat, 24 May 1997 02:15:59 -0700 (PDT) Received: from nlsystems.com (nlsys.demon.co.uk [158.152.125.33]) by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id CAA15479 for ; Sat, 24 May 1997 02:15:56 -0700 (PDT) Received: from herring.nlsystems.com (herring.nlsystems.com [10.0.0.2]) by nlsystems.com (8.8.5/8.8.5) with SMTP id KAA07238; Sat, 24 May 1997 10:15:47 +0100 (BST) Date: Sat, 24 May 1997 10:15:47 +0100 (BST) From: Doug Rabson To: Michael Smith cc: chuckr@Glue.umd.edu, FreeBSD-Hackers@freebsd.org Subject: Re: 3COM stuff In-Reply-To: <199705240810.RAA05616@genesis.atrad.adelaide.edu.au> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk On Sat, 24 May 1997, Michael Smith wrote: > Doug Rabson stands accused of saying: > > > > > > NFS on those cards is _BAD_. If at all possible, do an FTP install. > > > If you must use NFS, make sure the rsize parameter is _small_ - I > > > recommend 1024 as a general rule. > > > > In theory, NFS over TCP should be usable with these cards. > > This is why? I would have thought that an 8k read would result in 8k > of packets, unless the window is somehow reduced through magic > knowledge of the card's receive capabilities...? TCP will break down the 8k result into MTU sized packets and will also be able to re-send in MTU sized packets if one is lost. The problem with the 3c503 is that NFS reads will send a burst of about 6 packets back-to-back which overflows the buffers. When the request times out, it re-sends and gets back another burst which overflows again. In TCP, the re-sending happens at a lower level and should work better with the limited buffering of the card. TCP will treat the buffer overflows as network congestion and back off. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 951 1891 Fax: +44 181 381 1039