From owner-freebsd-stable Tue Mar 20 11: 3:23 2001 Delivered-To: freebsd-stable@freebsd.org Received: from idiom.com (idiom.com [216.240.32.1]) by hub.freebsd.org (Postfix) with ESMTP id 839D337B71C for ; Tue, 20 Mar 2001 11:03:15 -0800 (PST) (envelope-from rdm@cfcl.com) Received: from cfcl.com (cpe-24-221-169-54.ca.sprintbbd.net [24.221.169.54]) by idiom.com (8.9.3/8.9.3) with ESMTP id LAA38337 for ; Tue, 20 Mar 2001 11:03:15 -0800 (PST) Received: from [192.168.168.205] (cerberus [192.168.168.205]) by cfcl.com (8.11.1/8.11.1) with ESMTP id f2KJ4QV59595 for ; Tue, 20 Mar 2001 11:04:27 -0800 (PST) (envelope-from rdm@cfcl.com) Mime-Version: 1.0 Message-Id: In-Reply-To: References: Date: Tue, 20 Mar 2001 10:53:23 -0800 To: freebsd-stable@FreeBSD.ORG From: Rich Morin Subject: Re: NFS performance Content-Type: text/plain; charset="us-ascii" ; format="flowed" Sender: owner-freebsd-stable@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG At 10:45 AM -0800 3/20/01, Gordon Tetlow wrote: >Why are you using TCP? If you are on a reliable LAN, use UDP. TCP should >be used for long haul NFS. There are lots of reasons for using UDP, if you >want me to go into them, I will. Although TCP imposes some overhead, it may provide better worst-case performance than UDP. Several years ago, I chatted with a friend (Stan Hanks, IIRC) who had been trying to figure out why X terminals were doing better than diskless workstations. It turned out that, when the Ethernet started to get overloaded, some packets would get lost. The (UDP-based) NFS code would then attempt to re-transmit the entire 8 KB block. Given that the net was already overloaded, this would typically fail. The X terminals, meanwhile, were able to get their packets through. It seems to me that TCP-based NFS would fare better in this scenario, because it would only retransmit Ethernet packets. I'm not sure whether the moral of this story is to use NFS, however; a more reasonable strategy might be to ensure that the net never gets that heavily loaded! -r -- http://www.cfcl.com/rdm - home page, resume, etc. http://www.cfcl.com/Meta/md_fb.html - The FreeBSD Browser email: rdm@cfcl.com; phone: +1 650-873-7841 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message