Dual core processors

[Bill Moran]

In response to Robert Fitzpatrick <lists at webtent.net>:

> I have a server with 6.1 and one dual-core processor and the SMP option
> was built in the kernel according to the doc below, but only zeros show
> up in the 'C' column of top after I've rebooted with the newly compiled
> kernel.
> 
>  http://www.freebsddiary.org/smp.php
> 
> I did not add APIC_IO as the doc suggested as it complains the option is
> invalid, plus I did not do this for my other 5.4 server which shows all
> processors in top. Both configs have a device of apic, neither has the
> APIC_IO option. However, the other server is running 2 physical CPU's
> and I see 0 thru 3 in the C column in top. Also, dmesg shows CPU #1
> Launched along with everything else:
> 
> esmtp# dmesg|grep CPU
> CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (3010.67-MHz 686-class CPU)
>   Logical CPUs per core: 2
> FreeBSD/SMP: Multiprocessor System Detected: 2 CPUs
> cpu0: <ACPI CPU> on acpi0
> acpi_throttle0: <ACPI CPU Throttling> on cpu0
> cpu1: <ACPI CPU> on acpi0
> SMP: AP CPU #1 Launched!
> 
> Why would I not see any other CPU numbers under top like I do in my
> other server?

Based on your dmesg, I don't believe you have a dual-cored CPU.  It
looks as if it's hyperthreaded, which is different.

Hyperthreading is disabled in FreeBSD by default because of possible
security issues.  It can be enabled by setting a sysctl ... I recommend
you do a bit of reading on the sysctl mechanism or it's behaviour might
confuse you.

-- 
Bill Moran
Collaborative Fusion Inc.



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