From owner-freebsd-hackers Sat Jun 12 18: 8:57 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from iquest3.iquest.net (iquest3.iquest.net [209.43.20.203]) by hub.freebsd.org (Postfix) with SMTP id 102AA14CE4 for ; Sat, 12 Jun 1999 18:08:54 -0700 (PDT) (envelope-from toor@dyson.iquest.net) Received: (qmail 18900 invoked from network); 13 Jun 1999 01:08:53 -0000 Received: from dyson.iquest.net (198.70.144.127) by iquest3.iquest.net with SMTP; 13 Jun 1999 01:08:53 -0000 Received: (from root@localhost) by dyson.iquest.net (8.9.1/8.9.1) id UAA05697; Sat, 12 Jun 1999 20:08:51 -0500 (EST) From: "John S. Dyson" Message-Id: <199906130108.UAA05697@dyson.iquest.net> Subject: Re: High syscall overhead? In-Reply-To: from Arun Sharma at "Jun 12, 99 11:09:48 am" To: adsharma@home.com (Arun Sharma) Date: Sat, 12 Jun 1999 20:08:51 -0500 (EST) Cc: dyson@iquest.net, freebsd-hackers@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL32 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > "John S. Dyson" writes: > > > Finegrained locking either requires developers with IQ's of 200 or higher, > > or a different kernel structure. I suggest that finegrained locking is cool, > > and can be intelligently used to mitigate (but not solve) the effects of > > lots of problems > > Fine grained locking is hard - but it isn't exactly rocket > science. It's been tackled in a number of OSes, papers have been > written about it. > I also have played with the SVR4 SMP kernel (the real working one), not some of the toys that called themselves SMP -- but later versions were much better than even what I worked on. I can say that the maintainability of the code sucked, and the problems were due to the ARCHITECTURE of the original kernel. Sure, it can be done, but it has to be done methodically, and simple non-SMP changes preciptate massive SMP changes. The typical monlithic kernels are just the right answer to the wrong problem, if you are talking optimal SMP solutions. > > Sure. But 2 and 4-way boxes are becoming more and more mainstream. And > any IO bound job is not going to perform well on FreeBSD because of > giant locking. > I agree. However, I suggest that finegrained locking will be a loosing proposition. Something in-between is probably good. My brains got fried on trying to figure out a GOOD solution for the FreeBSD kernel. There are no GOOD solutions, but a reasonable compromise is some kind of medium grained scheme. John To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message