Re: SMP speed on 6x86 UP

Pavel Machek (pavel@elf.ucw.cz)
Wed, 18 Mar 1998 21:23:06 +0100


Hi!

> > Anybody got any idea. May the APIC code touch chipset or processor
> > ports?
>
> i suspect it's the LOCK overhead. If it's a single-CPU system, then could
> you edit asm-i386/atomic.h, and do:

I doubt it could be _any_ kernel overhead. When machine goes down in
performance 3 times or so, it usually means that something is
misconfigured. Overhead in kernel does not hit user processes _that_
much and surely would not change bogomips.

> generally, the APIC(s) is rarely touched except at initialization
> time. So

Well, one bad shot into configuration register at init time is
probably just enough.

> it cant really be the APIC stuff. And it's _never_ supposed to be touched
> if it's not detected at bootup ...

Pavel

-- 
I'm really pavel@atrey.karlin.mff.cuni.cz. 	   Pavel
Look at http://atrey.karlin.mff.cuni.cz/~pavel/ ;-).

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