Date: Sun, 21 Jan 2001 13:29:39 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Dag-Erling Smorgrav <des@ofug.org> Cc: smp@FreeBSD.org Subject: RE: debug.witness_skipspin Message-ID: <XFMail.010121132939.jhb@FreeBSD.org> In-Reply-To: <xzp8zo469hj.fsf@flood.ping.uio.no>
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On 21-Jan-01 Dag-Erling Smorgrav wrote: > Is there a particular reason why this sysctl is read-only? Just for > laughs, I built a kernel with a writeable debug.witness_skipspin, and > experienced no ill effects from switching back and forth. Hmmm. I made it read only because you can get inconsistent state if, for example, witness is on when a lock is acquired but not when it is released. In that case, witness never notices that it is released and thinks the lock order is messed up when it isn't. Perhaps sysctl() is safe from this race however since spinlocks disable interrupts. > 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-smp" in the body of the message
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