[H-GEN] Single CPU shows up as dual CPU.

[Ewan Edwards]

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I think the answer is to do with the hyperthreading - see /proc/cpuinfo below.

On Mon, 4 Nov 2002 12:13, Robert Brockway wrote:
>
> It should always be safe to run an SMP capable kernel on a box with only 1
> cpu (unless there's a bug in the detection routing).  Can't say I've ever
> seen a box list usage stats for more cpus that it has though.

I recall now, setting up a dual P4 Xeon box about a year ago with Windoze 2000 
advanced server and the "task manager" utility thought it a quad CPU box.  
The story at the time was something like; new technology in the CPU silicon 
design that M$ hadn't a chance to allow for prior to Win2k being released.

>
> Are you sure it only has 1 cpu?  The top output your pasted really looks

Absolutely sure.  Not only did we order and pay for single cpu only, I looked 
inside the boxes when they arrived and remember seeing the empty white 
socket.

> like 2 real cpus. What do you get if you cat /proc/cpuinfo ?

<snip>
[root at diamond root]# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 2
model name      : Intel(R) XEON(TM) CPU 2.40GHz
stepping        : 4
cpu MHz         : 2392.278
cache size      : 512 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips        : 4771.02

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 15
model           : 2
model name      : Intel(R) XEON(TM) CPU 2.40GHz
stepping        : 4
cpu MHz         : 2392.278
cache size      : 512 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca 
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm
bogomips        : 4784.12

[root at diamond root]#
</snip>

>
> If it does only have 1 cpu, reboot the box & pass the switch "nosmp" to
> the kernel on boot (using your preferred boot loader).

Grub is configured to boot either the SMP or the UP kernel with the SMP being 
the default.  Which would I pass that switch to?  Or, would it be more 
sensible just to try booting the UP kernel instead?



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