Date: Sat, 11 Dec 2004 22:05:16 +0000 From: RW <list-freebsd-2004@morbius.sent.com> To: freebsd-questions@freebsd.org Subject: Re: [Fwd: HTT/SMP servers instability on 5.3-STABLE] Message-ID: <200412112205.17410.list-freebsd-2004@morbius.sent.com> In-Reply-To: <Pine.NEB.4.61.9.0412101953340.579@kenmore.kozy-kabin.nl> References: <36661.194.210.13.66.1102680032.squirrel@194.210.13.66> <41B9F042.4040700@raad.tartu.ee> <Pine.NEB.4.61.9.0412101953340.579@kenmore.kozy-kabin.nl>
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On Friday 10 December 2004 19:57, Colin J. Raven wrote: > On Dec 10, Toomas Aas launched this into the bitstream: > > Colin J. Raven wrote: > >> On Dec 10, Toomas Aas launched this into the bitstream: > >>> For more than a month now, I've been running a Dual Xeon 2000 system > >>> (IBM eServer xSeries 225) with 5.3-RC2 and later upgraded to > >>> 5.3-RELEASE and I have no problems at all. Hyperthreading is disabled > >>> in BIOS, ACPI is enabled. > >> > >> Excuse me for jumping into this thread but could you elaborate as to why > >> you have Nyperthreading disabled? > > > > I'm afraid I can't give you any good technical reasons. I simply think of > > HTT as Intel marketing blurb, meant to make you feel like you are getting > > two CPUs for the price of one. Well, actually it's still only one CPU. > > I've been running another single Xeon 2.4 box for more than a year. > > Initially, I ran several months with HTT enabled. Then I ran several > > months with HTT disabled. I didn't really notice any performance > > difference. > > Well thanks for sharing those observations. Until I read what you said I > *assumed* that there was a performance difference with HTT > enabled. The specs seem to show that there *is* a theoretical > difference, yet clearly according to your observations there just isn't > any difference of earth shaking proportions. Isn't the point of HTT that a CPU holds several threads from the *same* process. So if your software isn't multithreaded, there's no benifit. UNIX software tends to fork single-threaded process, rather than create new threads, so it benefits from SMP, but not HTT.
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