From owner-cvs-src@FreeBSD.ORG Wed Mar 10 13:09:08 2004 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from green.homeunix.org (freefall.freebsd.org [216.136.204.21]) by hub.freebsd.org (Postfix) with ESMTP id 8507416A4CE; Wed, 10 Mar 2004 13:09:07 -0800 (PST) Received: from green.homeunix.org (green@localhost [127.0.0.1]) by green.homeunix.org (8.12.10/8.12.9) with ESMTP id i2AL96Rt073172; Wed, 10 Mar 2004 16:09:06 -0500 (EST) (envelope-from green@green.homeunix.org) Received: from localhost (green@localhost)i2AL96dn073169; Wed, 10 Mar 2004 16:09:06 -0500 (EST) (envelope-from green@green.homeunix.org) Message-Id: <200403102109.i2AL96dn073169@green.homeunix.org> X-Mailer: exmh version 2.6.3 04/04/2003 with nmh-1.0.4 To: Poul-Henning Kamp In-Reply-To: Message from Poul-Henning Kamp <200403102041.i2AKf90l061660@repoman.freebsd.org> From: "Brian F. Feldman" Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 10 Mar 2004 16:09:05 -0500 Sender: green@green.homeunix.org cc: cvs-src@FreeBSD.org cc: src-committers@FreeBSD.org cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/sys mdioctl.h src/sys/dev/md md.c src/sbin/mdconfig mdconfig.8 mdconfig.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Mar 2004 21:09:08 -0000 Poul-Henning Kamp wrote: > In addition to more closely emulating a real disk device with a > non-lying write-cache, this makes the writes exempt from rate-limited > (there to avoid starving the buffer cache) and consequently prevents > the deadlock. > > Unfortunately performance takes a hit. > > Add "async" option to give people who know what they are doing the > old behaviour. Could you please implement an errx(3) for MD_ASYNC without MD_FORCE, or something of that ilk? Users who use anything other than mdconfig(8) for leanring how to use mdconfig(8) could quite easily run across something like: "Make sure to use -o async to get better performance." and shoot themselves in the foot, whereas if they saw: "Make sure to use -o force -o async..." or "Make sure to use -o (dangerous|unsafe|deadlock_prone)_async..." they would be better aware of the risks. Just changing the option to make it obvious to the user that the option is not just asynchronous but also dangerous moves the warning documentation to a more visible location. This is tools, not policy, but anything that, at little cost, increases anti-foot-shooting capabilities of the tools is a Good Thing, IMHO. -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\