From: Frank van Maarseveen Subject: Re: [PATCH 4/5] NFSD: Remove NFSD_TCP kernel build option Date: Tue, 5 Feb 2008 19:08:19 +0100 Message-ID: <20080205180819.GA12916@janus> References: <20080205000442.18602.29035.stgit@manray.1015granger.net> <47A7AB89.7020709@melbourne.sgi.com> <1202170754.28484.57.camel@heimdal.trondhjem.org> <47A7AE03.10401@melbourne.sgi.com> <4BE5A1AE-DB3B-4796-B6BD-5691930258C8@oracle.com> <47A7F8F3.3020907@melbourne.sgi.com> <20080205155021.GA7805@janus> <1202233839.8452.31.camel@heimdal.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Greg Banks , Chuck Lever , bfields@citi.umich.edu, linux-nfs@vger.kernel.org To: Trond Myklebust Return-path: Received: from frankvm.xs4all.nl ([80.126.170.174]:36652 "EHLO janus.localdomain" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758408AbYBESIU (ORCPT ); Tue, 5 Feb 2008 13:08:20 -0500 In-Reply-To: <1202233839.8452.31.camel-rJ7iovZKK19ZJLDQqaL3InhyD016LWXt@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Tue, Feb 05, 2008 at 12:50:39PM -0500, Trond Myklebust wrote: > > On Tue, 2008-02-05 at 16:50 +0100, Frank van Maarseveen wrote: > > Last time I checked (around 2.6.22) writing large files on NFSv3 over > > UDP was 20% faster compared to TCP (Gb LAN with one switch connecting > > all machines). > > > > TCP and its timeout/retransmission behavior isn't always the best choice. > > If your environment has only 1 client working against a dedicated NFS > server on a clean network, then that may indeed be the case, but as soon > as you have more than 1 client, TCP almost always ends up outperforming > UDP. There are multiple clients (12 per physical server on average) but the clients generally don't write (or read) at the same time. Anyway, I'll keep this in mind. -- Frank