Julian Elischer wrote: > Robert Watson wrote: >> >> On Thu, 12 Apr 2007, Dag-Erling Smørgrav wrote: >> >>> Randall Stewart <rrs_at_cisco.com> writes: >>>> machdep.hyperthreading_allowed: 0 >>> >>> Note that enabling hyperthreading is more likely to harm performance >>> than to help it. You should just disable it in the BIOS, and run a >>> UP kernel. >> >> Historically this has been true, but some more recent results I've >> seen suggest that both hyperthreading hardware has improved, and the >> efficiency of our SMP implementation and scheduler has lead to it >> being more effective used. I would reevaluate this on more modern >> hardware and using a more recent kernel before assuming this remains >> true for your application. > > In addition to this, to answer the original question, I remember a > commit so that if you disable a cpu (or HT cpu) it doesn't get counted > in the CPU % so if you have 2 cpus and disable one hten prior to that > commit it was not possible to get > 50% busy but after that commit > you could get 100% "of the available CPUs". That fix is not (I believe) > in 6.2. That's correct. The fix went in after RELENG_6_2 has been branched. -MaximReceived on Thu Apr 12 2007 - 20:39:16 UTC
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