Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!mimsy!chris From: chris@mimsy.UUCP (Chris Torek) Newsgroups: comp.unix.wizards Subject: Re: Information on BSD 4.[23] on two/multiple processor systems Message-ID: <7884@mimsy.UUCP> Date: Thu, 6-Aug-87 10:22:20 EDT Article-I.D.: mimsy.7884 Posted: Thu Aug 6 10:22:20 1987 Date-Received: Sat, 8-Aug-87 12:45:54 EDT References: <1112@elrond.CalComp.COM> Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742 Lines: 45 Keywords: BSD 4.[23] Multiple Processor Systems In article <1112@elrond.CalComp.COM> adb@elrond.CalComp.COM (Alan D. Brunelle) writes: > We are seeking any information on BSD 4.2 or 4.3 support of multiple CPU > systems. (More specifically a two CPU system such as a VAX 11/782 or > VAX 8800.) The types of information we are most interested in are: > o Does the standard BSD 4.[23] release support the dual processor > systems? No; and in any case, 4.3BSD does not run on BI machines like the 8800 (except here at the University of Maryland!). Ultrix 2.0 appears to support multiple CPUs, and it is not terribly difficult to add similar support to 4.3BSD. Most of the hooks are there; this is what `masterpaddr' in Swtch() is all about. George Goble at Purdue has had a master/slave system running for years, using an inexpensive version of the 782 (replace the SBI terminator with a second KA780 and away you go). > o To what extent is the 2nd processor utilized? (Is it a true > multi-processor port in that the kernel and user processes can > run on either CPU, or is it the case that the kernel runs on one > and only one of the CPUs?) The obvious changes for 4.3 result in a master/slave system. Allowing any CPU to make syscalls and field interrupts requires real locking, which would require fairly substantial kernel changes. Just ask Sequent: they did it. I would guess that Ultrix 2.0 uses master/slave. > o Are there any performance measures which compare a two processor > system vs. the single processor version? (Using the same kernel > source on a single processor system vs. a two processor system, > does the two processor version equal 1.3? 1.5? 1.7? 2.0!? times > a single processor system?) The answer is `it depends'. Master/slave systems run anywhere from <1.0 to 1.9+ times the rate of single-cpu systems, depending on exactly what you do. Consult any good operating systems book for details. > "Elen sila lumenn' omentielvo." Be careful, friends! Speak no secrets! :-) -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690) Domain: chris@mimsy.umd.edu Path: seismo!mimsy!chris