From owner-freebsd-current@FreeBSD.ORG Tue Feb 24 11:29:34 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 226C716A4CE; Tue, 24 Feb 2004 11:29:34 -0800 (PST) Received: from fledge.watson.org (fledge.watson.org [204.156.12.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id ADFFA43D46; Tue, 24 Feb 2004 11:29:33 -0800 (PST) (envelope-from robert@fledge.watson.org) Received: from fledge.watson.org (localhost [127.0.0.1]) by fledge.watson.org (8.12.10/8.12.10) with ESMTP id i1OJShDL059289; Tue, 24 Feb 2004 14:28:43 -0500 (EST) (envelope-from robert@fledge.watson.org) Received: from localhost (robert@localhost)i1OJShis059286; Tue, 24 Feb 2004 14:28:43 -0500 (EST) (envelope-from robert@fledge.watson.org) Date: Tue, 24 Feb 2004 14:28:43 -0500 (EST) From: Robert Watson X-Sender: robert@fledge.watson.org To: Willem Jan Withagen In-Reply-To: <079d01c3fb06$0e2299b0$471b3dd4@dual> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-performance@FreeBSD.ORG cc: current@FreeBSD.ORG Subject: Re: The effects of WITNESS and INVARIANTS X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 Feb 2004 19:29:34 -0000 On Tue, 24 Feb 2004, Willem Jan Withagen wrote: > Just out of curriousity, and 'cause I've got some idle boxes, I started > to do some (NFS-)performance testing. There is still a long way to go, > but I've but a first obvious result online running on the local server > disk. > > It makes the claims of the effects of WITNESS and INVARIANTS very > obvious. Look especially at the graph for "Sequential block read". > > You might want to have a look at: > http://withagen.dyndns.org/FreeBSD/nfs-performance/index.html. Note > that no NFS data is included. I have some Bonnie-NFS data, but need to > write accompanying test and conclusions for it. > > Suggestions are more than welcomed. My primary suggestion is "Turn off WITNESS and INVARIANTS when benchmarking or for production systems". We turn them off in releases, and once 5.x becomes 5-stable, we'll turn it off by default also. However, they're invaluable tools when debugging the development system, so we have them on in the development branch by default. I would encourage people to generally run with them turned on unless performance of a system requires them to be off, as it really helps the debugging process, as well as helping to identify locking problems as the system evolves. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research