Date: 15 Jun 1999 11:20:11 +0300 From: Ville-Pertti Keinonen <will@iki.fi> To: mo@servo.ccr.org (Mike O'Dell) Cc: hackers@freebsd.org Subject: Re: coarse vs fine-grained locking in SMP systems Message-ID: <86btehooxw.fsf@not.demophon.com> In-Reply-To: mo@servo.ccr.org's message of "14 Jun 1999 13:48:19 %2B0300" References: <199906141047.GAA57400@servo.ccr.org>
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mo@servo.ccr.org (Mike O'Dell) writes: > very fine-grain-locked systems often display convoying and > are prone to priority inversion problems. coarse-grained Priority inversion problems are design flaws. Depending on the type of locks, they may not even be possible. Spin locks held for short periods of time (typical for very fine-grained systems) can't cause priority inversion because the process holding the lock can't block. > we published the best Unix SMP paper I've ever seen in Computing > Systems - from the Amdahl guys who did an SMP version of the kernel > by very clever hacks on SPLx() macros to make them spin locks and > a bit of other clever trickery on the source. they could take a stock An approach like that can't possibly be sufficient if code has been written with the assumption that only interrupt-like events or blocking calls can change things from under it. There is quite a bit of code in FreeBSD that relies on this. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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