Return-Path: Received: from mx2.redhat.com ([66.187.237.31]:34655 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751329AbZFELiG (ORCPT ); Fri, 5 Jun 2009 07:38:06 -0400 Message-ID: <4A2902E6.2080006@RedHat.com> Date: Fri, 05 Jun 2009 07:35:02 -0400 From: Steve Dickson To: Neil Brown , Greg Banks CC: Brian R Cowan , linux-nfs@vger.kernel.org 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> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 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? 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.