Also seeing 2 x quad-core system slower that 2 x dual core
kris at FreeBSD.org
Fri Nov 30 07:41:59 PST 2007
Pete French wrote:
>> Yes, if the claim is that the hardware is absolutely identical apart
>> from one having two quad-core CPUs instead of two dual-core, the next
>> step is to disable half of the CPUs and confirm that the problem goes away.
> Just comming back to this today, will do a side by side compare of the dmesg
> later to make sure that they *are* identical as claimed, but the idea of
> disabling half the CPU's is an excellent one!
> Aha, brilliant idea!
>> Check dmesg for the APIC numbers corresponding to the CPUs you want to
>> disable and add the corresponding entries to /boot/loader.conf, e.g.:
> You mean this bit?
> FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs
> cpu0 (BSP): APIC ID: 0
> cpu1 (AP): APIC ID: 1
> cpu2 (AP): APIC ID: 2
> cpu3 (AP): APIC ID: 3
> cpu4 (AP): APIC ID: 4
> cpu5 (AP): APIC ID: 5
> cpu6 (AP): APIC ID: 6
> cpu7 (AP): APIC ID: 7
> gives me...
> rebooting now to give it a try...
Well, the "1" is a boolean so those values will probably also work, but
the point was to disable apics 1,3,5 and 7 on the left hand side :) In
your case those are also valid but sometimes they are other numbers.
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