How to identify if there is some power saving setting that powered down a processor in Linux

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I have a linux server that apparently has two Intel Xeon X5670.

/proc/cpuinfo shows 12 CPUs but dmidecode shows only one CPU and the other one is in the Unpopulated status like it is showing that this is other CPU is because of the hyper threading.

My server is a HP Proliant DL380 G7 and it can have up to two CPUs.

My question is if my server has one or two physical CPUs or if there is a setting that is powering down the second CPU so it is showing as Unpopulated in the socket.

root@linux:~ # cat /proc/cpuinfo | grep processor processor       : 0
processor       : 1 processor       : 2 processor       : 3 processor 
: 4 processor       : 5 processor       : 6 processor       : 7
processor       : 8 processor       : 9 processor       : 10 processor
: 11

root@linux:~ # dmidecode --type processor| egrep
"Version|Family|Manufacturer|Socket|Status"
        Socket Designation: Proc 1
        Family: Xeon
        Manufacturer: Intel
        Signature: Type 0, Family 6, Model 44, Stepping 2
        Version: Intel(R) Xeon(R) CPU X5670 @ 2.93GHz
        Status: Populated, Enabled
        Upgrade: Socket LGA1366
        Socket Designation: Proc 2
        Family: Xeon
        Manufacturer: Intel
        Signature: Type 0, Family 0, Model 0, Stepping 0
        Version:
        Status: Unpopulated
        Upgrade: Socket LGA1366

Best Answer

If I read the datasheet correctly, you have one slot filled, six cores, which show as 12 processors because they are hyperthreading. (Also, /proc/cpuinfo should tell you about processor and physical id. The two parts of a hyperthreading core have the same physical id.)

This seems like a good read on the matter.

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