Date: Mon, 28 Feb 2000 14:08:03 -0300 (EST) From: Fabio Cesar Gozzo <fabio@iqm.unicamp.br> To: jim@reptiles.org (Jim Mercer) Cc: bart@ixori.demon.nl, freebsd-smp@FreeBSD.ORG Subject: Re: current working SMP mboards? Message-ID: <200002281708.OAA73898@thomson.iqm.unicamp.br> In-Reply-To: <20000228112140.L606@reptiles.org> from Jim Mercer at "Feb 28, 2000 11:21:40 am"
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Jim Mercer wrote: >On Mon, Feb 28, 2000 at 05:03:57PM +0100, Bart van Leeuwen wrote: >> Its important to realize that a single instance of an application can >> only be run by 2 cpus simultaniously if it is multi threaded. A non >> multi threaded app is unlikely to show any performance gain on smp. What >> SMP does do in such cases however is make that you can run more on that >> machine.. ie, it doesn't get faster, it gets more capacity. (ie, the >> capacity to run a 2nd instance of an application without any impact on >> the first instance) > >assuming disk I/O is not a factor (which it may be), if i have a process which >is processor intensive, i can run two instances of that process in parallel, >right? so if the process takes 30 seconds to complete, then it would be >60 seconds in serial, and 30 seconds (plus something no doubt) in parallel. > >or are you saying that even when running the processes in parallel, that >there are wait-states or something that would make the parallel running time >similar to the serial running time? If you are looking for experiences, I've been running a parallel calculation program on ASUS P2B-DS (latest 4.0 snapshot) having a gain ranging from 1.8 to 1.95. Of course, that depends on the parallel implementation. My program uses fork()/wait() to spaw another process. YMMV. -- ************************************************** Fabio Gozzo fabio@iqm.unicamp.br State University of Campinas UNICAMP Chemistry Institute http://thomson.iqm.unicamp.br ************************************************** To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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