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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!gmi!zombie.ncsc.mil!MathWorks.Com!europa.eng.gtefsd.com!library.ucla.edu!ihnp4.ucsd.edu!ames!newsfeed.gsfc.nasa.gov!cesdis1.gsfc.nasa.gov!not-for-mail From: becker@cesdis.gsfc.nasa.gov (Donald Becker) Newsgroups: comp.os.386bsd.misc Subject: Re: dual processor motherboards the way forward? Date: 4 Oct 1994 16:39:37 -0400 Organization: NASA Goddard Space Flight Center -- Greenbelt, Maryland USA Lines: 33 Message-ID: <36sei9$g3j@cesdis1.gsfc.nasa.gov> References: <Cww6x9.1A0@gnome.co.uk> NNTP-Posting-Host: cesdis1.gsfc.nasa.gov Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit In article <Cww6x9.1A0@gnome.co.uk>, Dr Chris Stenton <jacs@gnome.co.uk> wrote: >I have just had some information sent to me on a dual pentium PCI-EISA >motherboard which is now availablle. The blurb says that there is some >crude (my word) support under windows NT where you can select an >application to run on the second processor. This made think what use >this additional technology could have for intel based unix. Would it >be better to just place the kernel on one processor and run all other >processes on the other; or some form of dynamic load balance which >will have some overhead? Anyway I am sure the FreeBSD and NetBSD teams >could have some fun with this after they have tired with porting 4.4 >BSD. I've look at a few of the dual P5 motherboards, and I've concluded that the current generation will never be more than a niche product. Their primary advantage is low cost -- a two processor motherboard costs about the same as two single processor motherboards. Their primary disadvantage is low scalability and relatively low performance. The boards are designed so that the P5 processors share everything, including the L2 cache and path to main memory. This limits the performance gain of adding the second process to well under a factor of two. I'm sure that there are a few applications where its possible to get an extra 25-50%, but it hardly seems worth redesigning a whole software system for such minimal gain. IMO, more processors running in a loosely-coupled cluster offers a much better performance gain, without locking you into a specific hardware configuration. -- Donald Becker becker@cesdis.gsfc.nasa.gov USRA-CESDIS, Center of Excellence in Space Data and Information Sciences. Code 930.5, Goddard Space Flight Center, Greenbelt, MD. 20771 301-286-0882 http://cesdis.gsfc.nasa.gov/pub/people/becker/whoiam.html