[Gllug] Dual core

[Daniel P. Berrange]

On Tue, May 15, 2007 at 02:17:30PM +0100, Yashpal Nagar wrote:
> Hi!
> 
> How do we figure out if the CPU is dual core? i am running RHEL 3/4 and 
> SUSE 10.
> I have used lshw, /proc/cpuinfo but none of them tell this arch of CPU.

The cpuinfo file has a 'physical id' field which refers to the physical
socket the logical CPU is in. So if two CPUs have same physical ID, then 
are a pair of cores in the same socket.

eg

$ grep -E '(processor|physical)' /proc/cpuinfo 
processor       : 0
physical id     : 0
processor       : 1
physical id     : 0

...Shows a single physical CPU, with two cores


# grep -E '^(processor|physical)' /proc/cpuinfo
processor       : 0
physical id     : 0
processor       : 1
physical id     : 3
processor       : 2
physical id     : 0
processor       : 3
physical id     : 3

...shows a pair of physical CPUs, each with two cores.

NB, I'm ignoring hyperthreading here which would also show us as two
cpus with same physical id - you'd need other heuristics to distinguish
a pair of cores, from a pair of hyperthreads.

Dan.
-- 
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