Find actual Physical CPU count, Cores in a server running Linux

Environment:

> cat /etc/*-release | grep -i linux

SUSE Linux Enterprise Server 10 (x86_64)

The well-known command…

-- In the below example, the /proc/cpuinfo shows processor listing starting from 0 and goes upto 15. So, a total count of 16. So from the below example, how do we figure out the actual count of physical CPU, cores, hyper threading, etc.

> cat /proc/cpuinfo

processor       : 0

vendor_id       : GenuineIntel

cpu family      : 6

model           : 26

model name      : Intel(R) Xeon(R) CPU           X5570  @ 2.93GHz

stepping        : 5

cpu MHz         : 2926.103

cache size      : 8192 KB

physical id     : 1

siblings        : 8

core id         : 0

cpu cores       : 4

fpu             : yes

fpu_exception   : yes

cpuid level     : 11

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 syscall nx rdtscp lm constant_tsc pni monitor ds_cpl vmx est tm2 cx16 xtpr dca popcnt lahf_lm

bogomips        : 5857.34

clflush size    : 64

cache_alignment : 64

address sizes   : 40 bits physical, 48 bits virtual

power management:

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processor       : 15

vendor_id       : GenuineIntel

cpu family      : 6

model           : 26

model name      : Intel(R) Xeon(R) CPU           X5570  @ 2.93GHz

stepping        : 5

cpu MHz         : 2926.103

cache size      : 8192 KB

physical id     : 0

siblings        : 8

core id         : 3

cpu cores       : 4

fpu             : yes

fpu_exception   : yes

cpuid level     : 11

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 syscall nx rdtscp lm constant_tsc pni monitor ds_cpl vmx est tm2 cx16 xtpr dca popcnt lahf_lm

bogomips        : 5852.07

clflush size    : 64

cache_alignment : 64

address sizes   : 40 bits physical, 48 bits virtual

power management:

-- Things to look out for

- processor count – 16 in our case

- siblings – 8 in our case

- cores – 4 in our case

- flags – look for "ht" in flags for hyper threading

-- Calculation

physical cpu = processor count/ siblings

physical cpu = 16/8 = 2 CPU (We have a 2 CPU machine)

cores = number of individual cores in a single cpu

cores = cpu cores = 4

               

                So it is a 2 CPU, 4 core machine with ht enabled.

                2 CPU * 4 Cores * 2(ht enabled) = 16 CPU in /proc/cpuinfo

-- To do a quick check directly from command line

- How many physical processors are there?

> grep 'physical id' /proc/cpuinfo | sort | uniq | wc -l

2

- How many virtual processors are there?

> grep processor /proc/cpuinfo | wc -l

16