Return-Path: Received: from qmta08.westchester.pa.mail.comcast.net ([76.96.62.80]:34142 "EHLO QMTA08.westchester.pa.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751692AbZFENFc (ORCPT ); Fri, 5 Jun 2009 09:05:32 -0400 Message-ID: <4A29181A.1080508@gmail.com> Date: Fri, 05 Jun 2009 09:05:30 -0400 From: Tom Talpey To: Steve Dickson CC: Linux NFS Mailing List Subject: Re: Link performance over NFS degraded in RHEL5. -- was : Read/Write NFS I/O performance degraded by FLUSH_STABLE page flushing References: <1243615595.7155.48.camel@heimdal.trondhjem.org> <1243618500.7155.56.camel@heimdal.trondhjem.org> <1243686363.5209.16.camel@heimdal.trondhjem.org> <1243963631.4868.124.camel@heimdal.trondhjem.org> <18982.41770.293636.786518@fisica.ufpr.br> <1244049027.5603.5.camel@heimdal.trondhjem.org> <4A2902E6.2080006@RedHat.com> In-Reply-To: <4A2902E6.2080006@RedHat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On 6/5/2009 7:35 AM, Steve Dickson wrote: > Brian R Cowan wrote: >> Trond Myklebust wrote on 06/04/2009 02:04:58 >> PM: >> >>> Did you try turning off write gathering on the server (i.e. add the >>> 'no_wdelay' export option)? As I said earlier, that forces a delay of >>> 10ms per RPC call, which might explain the FILE_SYNC slowness. >> Just tried it, this seems to be a very useful workaround as well. The >> FILE_SYNC write calls come back in about the same amount of time as the >> write+commit pairs... Speeds up building regardless of the network >> filesystem (ClearCase MVFS or straight NFS). > > Does anybody had the history as to why 'no_wdelay' is an > export default? Because "wdelay" is a complete crock? Adding 10ms to every write RPC only helps if there's a steady single-file stream arriving at the server. In most other workloads it only slows things down. The better solution is to continue tuning the clients to issue writes in a more sequential and less all-or-nothing fashion. There are plenty of other less crock-ful things to do in the server, too. Tom. As Brian mentioned later in this thread > it only helps Linux servers, but that's good thing, IMHO. ;-) > > So I would have no problem changing the default export > options in nfs-utils, but it would be nice to know why > it was there in the first place... > > Neil, Greg?? > > steved. > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >