Date: Mon, 14 Jun 1999 06:47:58 -0400 (EDT) From: "Mike O'Dell" <mo@servo.ccr.org> To: hackers@freebsd.org Subject: coarse vs fine-grained locking in SMP systems Message-ID: <199906141047.GAA57400@servo.ccr.org>
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very fine-grain-locked systems often display convoying and are prone to priority inversion problems. coarse-grained systems exhibit all the granularity problems already described. (the first purdue dual-vax system plowed most of that ground) 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 kernel and SMP everything but the device drivers essentially with a SED script. most interesting, they benchmarked it against their laboriously reworked fine-grained kernel and under heavy multiprogramming loads it performed better than the fine-grain kernel and essentially never did materially worse. and with *many* fewer man-years of hacking. it might be worth digging out that paper for a looky. sorry i don't have the citation off the top of my head, but i think the Usenix online index would have it. -mo To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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