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To: kometen@gmail.com, kris@FreeBSD.org
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From: Pete French <petefrench@ticketswitch.com>
Date: Fri, 30 Nov 2007 11:33:51 +0000
Cc: max@love2party.net, freebsd-stable@freebsd.org
Subject: Re: Also seeing 2 x quad-core system slower that 2 x dual core
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> 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

> hint.lapic.1.disable="1"
> hint.lapic.3.disable="1"
> hint.lapic.5.disable="1"
> hint.lapic.7.disable="1"

gives me...

hint.lapic.1.disable="1"
hint.lapic.3.disable="3"
hint.lapic.5.disable="5"
hint.lapic.7.disable="7"

rebooting now to give it a try...

-pete.