Date: Thu, 22 Feb 2001 06:31:18 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Dag-Erling Smorgrav <des@ofug.org> Cc: current@FreeBSD.org, "Alexander N. Kabaev" <ak03@gte.com>, Maxim Sobolev <sobomax@FreeBSD.org> Subject: Re: A possible bug in the interrupt thread preemption code [Was: Message-ID: <XFMail.010222063118.jhb@FreeBSD.org> In-Reply-To: <xzpofvulrt5.fsf@flood.ping.uio.no>
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On 22-Feb-01 Dag-Erling Smorgrav wrote: > John Baldwin <jhb@FreeBSD.org> 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 <jhb@FreeBSD.org> -- 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
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