Date: Fri, 12 Mar 2004 12:02:43 -0500 From: "Simon" <simon@optinet.com> To: "Artem Koutchine" <matrix@itlegion.ru>, "freebsd-hardware@freebsd.org" <freebsd-hardware@freebsd.org> Subject: Re: Multiprocessor system VS one processor system Message-ID: <20040312170213.BB03143D45@mx1.FreeBSD.org> In-Reply-To: <002f01c4081c$bd720810$0c00a8c0@artem>
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While FreeBSD 4.9 can only run one process per CPU, in a multi-user environment, you will have multiple processes running on multiple CPUs at the same time. You can't do this with 1 CPU, even if that one CPU is faster. Of course, an outdated dual CPU server is not a lot faster than a 2x+ faster newer single CPU server. FreeBSD 5.x is going to change this all, read: http://www.lemis.com/grog/SMPng/Singapore/paper.pdf -Simon On Fri, 12 Mar 2004 13:28:18 +0300, Artem Koutchine wrote: >Hi! > >I need to understand something very clear. > >As I understand FreeBSD (as of 4.9) runs one process >per one CPU. This means, that if i have dual systems >with 500Mhz CPUs one process can never run faster >than on a single 500Mhz CPU. However, if i substitute >those two CPUs with one 1000Mhz, that one process will run >twice as fast than on dual 500Mhz, however, to box will >become a bit less responsive, because in a dual box >when one CPU is loaded, another one may have some >spare time to respond. However, in case of very loaded >box both CPUs a extremely loaded and the box will >be as responsive as single 1000Mhz CPU box 100% loaded. >So, according to what i just said there is not real reason to >setup a dual CPU box under FREEBSD unless you want to >have 5000Mhz box, but there is no CPU with such speed, so >you put two 2500Mhz CPU in it and if you are running a lot >of processes with short run periods you will get overal >perfomance somewhere near 5000Mhz. However, when i >subsituted two 500Mhz CPUs with 1500Mhz one (even with >less 2nd level cache) on a heavy loaded web server i notice >that sites started to load faster. So, it seems as >one 3X Mhz CPU is faster that two X MHz CPUs, at least >for web server with sql base and many perl scripts. > >So, there are two questions: >1) Am I right or am wrong? >2) Does FreeBSD 5.X run one process only on one CPU >or it can run on thread of a process on one CPU and another >thread on another CPU? > >Regards, >Artem >_______________________________________________ >freebsd-hardware@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-hardware >To unsubscribe, send any mail to "freebsd-hardware-unsubscribe@freebsd.org" >
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