Messages in this thread |  | | | Date | Wed, 18 Mar 1998 00:47:33 +0000 | | From | Brian Gerst <> | | Subject | Re: SMP speed on 6x86 UP |
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Kurt Garloff wrote: > > Hi, > > I tested the implementation of spinlocks in 2.1.89 and booted an SMP kernel > on my single CPU machine (FIC PA-2010, VIA Apollo VP, 1xIBM 6x86-P166+ at > 133 MHz) and the bogomips (= frequency in MHz on this CPU) dropped from 133 > to 33. Not only the bogusmips value drops but also the system performance. > With CPU intensive code, I see exactly the same thing: 1/4 of the > performance, I have with a UP kernel. > > Anybody got any idea. May the APIC code touch chipset or processor ports?
First off, bogomips are really a meaningless measurement. Every brand/model of processor can have a different bogomips rating for the same MHz speed. It is only a measure of how the processor handles tight loops. (ie, my K6-233 shows ~466 bogomips, a 2x factor, while my 6x86 showed a 1x factor) The 6x86 wasn't designed to do SMP (at least Intel's version of SMP), as it does not have a true APIC. Given that, I wouldn't even try to run an SMP kernel on a 6x86. Last time I tried (by accident) I got a ton of oopses.
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Brian Gerst
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