> I have what seems like a simple question.
It's not a simple question :-/
> I have a Dell PowerEdge 1300 which has a dual processor motherboard but is
> only fitted with one processor and some sort of 'dummy' board in the 2nd
> processor slot.
I'm not know about Dell PowerEdge 1300 but I have Dell PowerEdge 2300 with
similar configuration and you MUST use SMP kernel there (even when there
are in fact just one processor unit installed). Reason ? APIC ... All external
PCI devices on Dell PowerEdge 2300 (I almost sure for PowerEdge 1300 this is
true as well) are using APIC-extended interrupts (Linux marks them as IRQ 20,
IRQ 21, etc). So with UP kernel you simple will be unable to use your hardware.
> Having just installed Redhat 6.1 on the machine I find that it has
> installed 2.2.12-20smp by default (yes, I know that's a redhat-ism).
> My question is; Do you see a problem running the smp kernel with a single
> processor installed ?
Sometimes it's troublesome (in VERY rare situations: on some rare Cyrix and/or
AMD processors mostly), but usually it's just Ok. Slightly slower then UP
kernel, though. With PowerEdge you have no choices anyway.
> Excuse my ignorance, I have searched the archives and come up empty on this
> subject.
> I just have no idea what implications might be in running the smp kernel
> and as this machine is going to be a rather well used production squid
> server, I don't want it falling in a heap because I 'assumed' everything
> would be fine. By the way, the machine won't have a 2nd processor installed
> anytime soon.
> Any pointers or comments would be most appreciated.
Check your /proc/interrupts file. If there are APIC interrupts > 15IRQ (last
"normal" interrupt) listed as used for something then you have the same
situation as I am and SHOULD use SMP kernel.
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