From owner-freebsd-current Thu Feb 22 6:32: 6 2001 Delivered-To: freebsd-current@freebsd.org Received: from meow.osd.bsdi.com (meow.osd.bsdi.com [204.216.28.88]) by hub.freebsd.org (Postfix) with ESMTP id 3FD4937B491; Thu, 22 Feb 2001 06:32:04 -0800 (PST) (envelope-from jhb@FreeBSD.org) Received: from laptop.baldwin.cx (john@jhb-laptop.osd.bsdi.com [204.216.28.241]) by meow.osd.bsdi.com (8.11.2/8.11.2) with ESMTP id f1METLl89625; Thu, 22 Feb 2001 06:29:21 -0800 (PST) (envelope-from jhb@FreeBSD.org) Message-ID: X-Mailer: XFMail 1.4.0 on FreeBSD X-Priority: 3 (Normal) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: Date: Thu, 22 Feb 2001 06:31:18 -0800 (PST) From: John Baldwin To: Dag-Erling Smorgrav Subject: Re: A possible bug in the interrupt thread preemption code [Was: Cc: current@FreeBSD.org, "Alexander N. Kabaev" , Maxim Sobolev Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On 22-Feb-01 Dag-Erling Smorgrav wrote: > John Baldwin writes: >> On 22-Feb-01 Maxim Sobolev wrote: >> > It's already have INVARIANTS, MUTEX_DEBUG, WITNESS and WITNESS_DDB. >> Hmm, ouch, you do'nt want MUTEX_DEBUG, that'll slow your system to a crawl. > > For the same reason, you probably want WITNESS_SKIPSPIN. Not really. WITNESS doesn't really bog down spin mutexes all that much. It has a very simple order checking that is nothing like the order checking for sleep mutexes. The killer for MUTEX_DEBUG is that each mtx_init() involves walking a linked list of _all_ of the mutexes in the system and checking each one with the one beign init'd to check for a duplicate init. > WITNESS_DDB is a bad idea, BTW, there's a (presumably harmless) lock > order reversal in the FS code that you're practically guaranteed to to > hit during boot. Well, they aren't necessarily harmless, but they've been around for a very long time, so if they do cause rare lockups, they are rare at least. > DES > -- > Dag-Erling Smorgrav - des@ofug.org -- John Baldwin -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message