From owner-freebsd-current Tue May 4 12:14:32 1999 Delivered-To: freebsd-current@freebsd.org Received: from herring.nlsystems.com (nlsys.demon.co.uk [158.152.125.33]) by hub.freebsd.org (Postfix) with ESMTP id 958C714E09 for ; Tue, 4 May 1999 12:14:10 -0700 (PDT) (envelope-from dfr@nlsystems.com) Received: from localhost (dfr@localhost) by herring.nlsystems.com (8.9.3/8.8.8) with ESMTP id UAA53747; Tue, 4 May 1999 20:14:00 +0100 (BST) (envelope-from dfr@nlsystems.com) Date: Tue, 4 May 1999 20:14:00 +0100 (BST) From: Doug Rabson To: Tony Finch Cc: current@freebsd.org Subject: Re: NFS Patch #8 for current available - new TCP fixes In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tue, 4 May 1999, Tony Finch wrote: > Matthew Dillon wrote: > > > > (fanfair!) > > :-) > > > NFS attempts to realign packet buffers and trods all over the underlying > > mbufs. For TCP connections, several RPC's may be present in an mbuf > > chain. The realignment of one of them may destroy the others. This does > > not occur with UDP because each UDP packet contains only a single rpc. > > > > Packet buffers may be unaligned for a number of reasons. The main reason > > is due to the 14 byte MAC header on the ethernet frame. This causes the > > remainder of the packet - the ip payload - to NOT be 4-byte aligned. > > We're planning to try replacing some Solaris web servers with FreeBSD > machines in the near future. The documents are on a read-only NFS > filestore connected to the web servers with CDDI. (Updates will stay > on a Sun box.) Are we going to have nfs_realign problems if we use TCP > in this situation or should we stick with UDP? I think UDP will probably work better. There won't be any problem with frames being re-ordered and the protocol overhead should be less. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message