Date: Fri, 28 Jun 2002 18:26:47 -0700 From: Peter Wemm <peter@wemm.org> To: Aaron Seelye <aseelye@urx.com> Cc: John David Duncan <jdd@greatschools.net>, freebsd-smp@FreeBSD.ORG, freebsd-stable@FreeBSD.ORG Subject: Re: 2 xeons = 4 CPUs? Message-ID: <20020629012647.422763917@overcee.wemm.org> In-Reply-To: <200206281803.45317.aseelye@urx.com>
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Aaron Seelye wrote:
> Yes, that's hyperthreading (as two others before me have said), but one thing
> to keep in mind is that you may want to disable it, as on some benchmarks it
> actually /slows down/ the system. YMMV.
The problem is that our naive scheduler assumes that all the cpu cores
are equal, and would easily schedule two tasks on the same chip while
leaving the other chip idle.
> Aaron
>
> On Friday 28 June 2002 02:52 pm, John David Duncan wrote:
> > Hey,
> >
> > I just installed 4.6-RELEASE on a dual 1.8Mhz Xeon + Tyan S2720
> > motherboard (a Relion 140 server from Penguin Computing, actually).
> > When I reboot with an SMP kernel, I see:
> >
> > CPU: Pentium 4 (2199.76-Mhz 686-class CPU)
> > CPU: Pentium 4 (2199.76-Mhz 686-class CPU)
> > CPU: Pentium 4 (2199.76-Mhz 686-class CPU)
> > CPU: Pentium 4 (2199.76-Mhz 686-class CPU)
> > SMP: AP CPU #1 Launched!
> > SMP: AP CPU #2 Launched!
> > SMP: AP CPU #3 Launched!
> >
> > That's twice as many CPUs as I think I have, each going 400Mhz faster. Is
> > this safe? Correct? Is it that hyperthreading stuff? Should I disable
> > it?
> >
> > Thanks
> >
> > - JD
> >
> >
> >
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>
>
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Cheers,
-Peter
--
Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
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