From owner-freebsd-hackers Mon Jun 14 3:48: 0 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from servo.ccr.org (servo.ccr.org [198.3.0.2]) by hub.freebsd.org (Postfix) with ESMTP id 0CDC614DB1 for ; Mon, 14 Jun 1999 03:47:58 -0700 (PDT) (envelope-from mo@servo.ccr.org) Received: (from mo@localhost) by servo.ccr.org (8.9.2/8.9.2) id GAA57400 for hackers@freebsd.org; Mon, 14 Jun 1999 06:47:58 -0400 (EDT) (envelope-from mo) Date: Mon, 14 Jun 1999 06:47:58 -0400 (EDT) From: "Mike O'Dell" Message-Id: <199906141047.GAA57400@servo.ccr.org> To: hackers@freebsd.org Subject: coarse vs fine-grained locking in SMP systems Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG 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