Messages in this thread | | | Date | Tue, 30 Apr 2002 00:20:19 +0200 | From | "J.A. Magallon" <> | Subject | Re: Hyperthreading and physical/logical CPU identification |
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On 2002.04.29 Andrew Theurer wrote: > >> > I would very much like to believe that in this configuration, >> > I am only >> > running on 2 physical, 4 logical processors, but I am getting a 31% >> > improvement (netbench) when hyperthreading is enabled. Thats >> > why I want to >> > confirm I am really only using 2 physical, 4 logical >> > processors. Is there >> > any way I can do this? (dmesg? /proc/cpuinfo?) >> >> Well the two alternatives are, either A) turning on hyperthreading enabled >> the two virtual processors or B) turning on hyperthreading somehow enabled >> the other two processors, right? >>
I think you should post a more specific "this vs. that" comparison. Guessing...
If you refer to: - No hypethreading, box sees 2 processors, performance is 100% - Hyperthreading active, box sees 4 processors, perf is _only_ 130%, instead of 200%.
that is perfectly true. Each hyperthreaded pair of processors does not perform like 2 independent ones, the share cache and other internal things. So the usual performance improvement on a FOster Xeon is not 200%, but in the order of that 130% you get. Hyperthreading is like 'poor man' SMP.
But perhaps you alredy know all this and your question was following other paths...
I will put my hands on a dual Xeon SuperMicro system, and will make more tests, in a week or so...
Hope this helps.
-- J.A. Magallon # Let the source be with you... mailto:jamagallon@able.es Mandrake Linux release 8.3 (Cooker) for i586 Linux werewolf 2.4.19-pre7-jam7 #1 SMP jue abr 25 00:19:56 CEST 2002 i686 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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