From: Olof Johansson Subject: Re: [PATCH] SVC sockets don't disable Nagle Date: Tue, 29 Apr 2003 19:07:21 -0500 Sender: nfs-admin@lists.sourceforge.net Message-ID: <3EAF13B9.8040402@austin.ibm.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Cc: trond.myklebust@fys.uio.no, nfs@lists.sourceforge.net Return-path: Received: from e31.co.us.ibm.com ([32.97.110.129]) by sc8-sf-list1.sourceforge.net with esmtp (Cipher TLSv1:DES-CBC3-SHA:168) (Exim 3.31-VA-mm2 #1 (Debian)) id 19Af8W-0002nb-00 for ; Tue, 29 Apr 2003 17:07:49 -0700 To: Bogdan Costescu 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: Bogdan Costescu wrote: > On Tue, 29 Apr 2003, Olof Johansson wrote: > >>Below patch disables it on the server side as well. For latency reasons, >>this should be the desired behaviour NFS at both client and server. > > > I disagree with this general statement. Nagle is there in the TCP protocol > for a specific reason and enabling or disabling it gives the opportunity > to better tune the connection. Yes, Nagle is there to reduce overhead by aggregating data into segments and piggybacking them with ACKs. Most significant differences will be when dealing with a steady but slow pace of characters, say text being typed over a 9600bps serial line. > It seems like disabling Nagle is the bolierplate answer for anyone who > encounters GigEth or better networking simply because the TCP protocol was > not designed for such fast networks. But what happens to others that do > not have GigEth ? What is the impact of this change for a slower/congested > network ? There is a chance that small requests and replies (~100 bytes) will not be aggregated into the same segments but instead sent out separately. In essence, this will result in some additional network overhead due to headers, but the response times will be perceived as faster even for slower networks. Since NFS traffic is bursty, it is unlikely that any individual request or reply will be split up between two segments when it didn't need to. > If anything, I would like to see this as a per-mount-point and > per-export-entry option... I think it would just clutter the documentation and list of options, since I don't forsee any practical scenarios in which anyone would have a positive performance impact from having Nagle enabled. On a side note: As far as I know, most (all?) other NFS implementations out there already disable Nagle. -Olof -- Olof Johansson Office: 4E002/905 pSeries Linux Development IBM Systems Group Email: olof@austin.ibm.com Phone: 512-838-9858 ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs