From owner-freebsd-current@FreeBSD.ORG Tue Oct 19 23:16:19 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 8183B16A4CE; Tue, 19 Oct 2004 23:16:19 +0000 (GMT) Received: from mail.vicor-nb.com (bigwoop.vicor-nb.com [208.206.78.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5FBAF43D1D; Tue, 19 Oct 2004 23:16:19 +0000 (GMT) (envelope-from julian@elischer.org) Received: from elischer.org (julian.vicor-nb.com [208.206.78.97]) by mail.vicor-nb.com (Postfix) with ESMTP id 474CD7A427; Tue, 19 Oct 2004 16:16:19 -0700 (PDT) Message-ID: <4175A043.8070209@elischer.org> Date: Tue, 19 Oct 2004 16:16:19 -0700 From: Julian Elischer User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.3.1) Gecko/20030516 X-Accept-Language: en, hu MIME-Version: 1.0 To: John Baldwin References: <20041019023713.GA1072@green.homeunix.org> <200410191650.28544.jhb@FreeBSD.org> <4175862C.6030403@elischer.org> <200410191729.42330.jhb@FreeBSD.org> In-Reply-To: <200410191729.42330.jhb@FreeBSD.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit cc: freebsd-current@freebsd.org cc: Robert Huff cc: Kris Kennaway Subject: Re: WITNESS bug 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, 19 Oct 2004 23:16:19 -0000 John Baldwin wrote: >On Tuesday 19 October 2004 05:25 pm, Julian Elischer wrote: > > >>John Baldwin wrote: >> >> >>>On Tuesday 19 October 2004 12:01 pm, Kris Kennaway wrote: >>> >>> >>>>On Tue, Oct 19, 2004 at 09:13:26AM -0400, Robert Huff wrote: >>>> >>>> >>>>>Brian Fundakowski Feldman writes: >>>>> >>>>> >>>>>>You should never not run with WITNESS_SKIPSPIN if you use >>>>>>modules. Any spin mutexes not listed statically in the witness >>>>>>code will cause your machine to immediately panic. >>>>>> >>>>>> >>>>> If this is true (and I'm not disputing it), shouldn't it be >>>>>noted in GENERIC and/or NOTES? For that matter, what's the penalty >>>>>for not automatically including it as part of WITNESS? >>>>> >>>>> >>>>Sometimes you don't want to use it, e.g. if you actually want to trace >>>>spinlock operations with witness. >>>> >>>> >>>True spin mutexes should be rarely used anyways, so I don't think modules >>>needing spin mutexes is all that big of an issue. Almost all mutexes >>>should just be regular mutexes. >>> >>> >>netgraph uses a spin mutex for it's node locks >> >> > >This is likely a bug, esp. given that normal mutexes adaptively spin when it >is advantageous to do so. :) > now that we have read-write locks it may be worth re looking at teh netgraph version of same to see if they can be used instead, but I doubt that the generic ones would be as lightweight. > > >