In Terminal nproc, OP: total cpu cores

Try this,

As per man lscpu

CORE   The logical core number. A core can contain several CPUs.



SOCKET The logical socket number. A socket can contain several cores.

cores as well as sockets are physical where as CPU(s) are logical number. So to find the number of cores your system has, do number of cores x number of sockets

A sample output of lscpu is as follows :

Thread(s) per core:    2

Core(s) per socket:    8

Socket(s):             2

So the total number of cores: 16

The total number of CPU(s): 32 (Since number of threads per core is 2)

As @Durga mentioned , the nproc gives total number of CPUs.

For more , refer this answer , to get interpretation of /proc/cpuinfo refer this

I'd like to thank @Kusalananda for helping me to understand the same.

Short Answer

The number of physical cores:

> cat /proc/cpuinfo | grep -m 1 "cpu cores"

cpu cores   : 2

The number of virtual cores (e.g. 2x number of physical cores with hyper threading):

> cat /proc/cpuinfo | grep -c "cpu cores"

4

If you have more than one CPU/processor (in this sense) on your mainboard this does not properly work. See section "Several CPUs per mainboard". This may be the case if you work on a computing cluster or on a high-end desktop workstation for CAD/Engineering-purposes.

Long Answer

The command cat /proc/cpuinfo should print out the number of physical cores in the line cpu cores. But it prints out this information for each virtual core. Thus, if you want to have the number of physical core, you just take the first occurrence of the line cpu cores, which is

> cat /proc/cpuinfo | grep -m 1 "cpu cores"

cpu cores   : 2

Alternatively, if you are looking for the number of virtual cores, you count the number of times the line cpu cores is found, which is

> cat /proc/cpuinfo | grep -c "cpu cores"

4

Example

I have got a Intel(R) Core(TM) i7-3740QM CPU @ 2.70GHz (4 physical cores, hyperthreading). Lets see what I get:

> cat /proc/cpuinfo | grep "cpu cores"

cpu cores   : 4

cpu cores   : 4

cpu cores   : 4

cpu cores   : 4

cpu cores   : 4

cpu cores   : 4

cpu cores   : 4

cpu cores   : 4

Number of physical cores:

> cat /proc/cpuinfo | grep -m 1 "cpu cores"

cpu cores   : 4

Number of virtual cores:

> cat /proc/cpuinfo | grep -l "cpu cores"

8

You could also take the last found processor number and increment it by one

> cat /proc/cpuinfo | grep "processor" | tail -1

processor   : 7

# +1

Several CPUs per mainboard

I just looked onto one node of a computing cluster, on which I am currently working: 1 node has 4 CPUs (Intel Xeon) with each 8 physical cores; each CPU supports hyptherthreading; therefore, each CPU has 16 virtual cores; summing it up, the one node has 32 physical and 64 virtual cores;

cat /proc/cpuinfo prints out information for each virtual core. Thus, we get 64 'packages' of information. If we have such a setup, we need to consider the row physical id in cat /proc/cpuinfo.

This is the output I get:

> cat /proc/cpuinfo | grep -m 1 "cpu cores"

cpu cores   : 8



> cat /proc/cpuinfo | grep -c "cpu cores"

64



> cat /proc/cpuinfo | grep "physical id" | tail -1

physical id   : 3

# this result +1 => number of CPUs

Thus, "number behind cpu cores" x "number behind physical id + 1" is the number of physical cores one our node (8 x (3 + 1)). The 64 is the number of virtual cores.

Nomenclature

Since everyone uses cores, CPU and processor in another context, I introduce a nomenclature for my answer here:

• processor: the whole piece of hardware (e.g. my Intel® Core™ i7-3740QM Processor)


• CPU: CPU = processor


• core or physical core: number of physical calculation units in the CPU


• thread or virtual core: number of threads that can run on parallel on one CPU; if the (intel-)processor is able to perform hyperthreading the number of virtual cores is twice the number of physical cores (I am not sure how other processor vendors call this feature);

__Example: __

• processor: Intel(R) Core(TM) i7-3740QM CPU @ 2.70GHz


• source: Intel Ark
  

Data:

• CPU number: 1


• processor number: 1


• cores (or physical cores): 4


• threads (or virtual cores): 8

If you have glibc and a reasonably recent kernel you can use

getconf _NPROCESSORS_ONLN

to return the number of currently online¹ processors. That includes virtual and hyper-thread processors.

¹ On most systems that will be identical to the number of overall processors. The exception are systems that have one or more processors disabled for whatever reason (e. g. because it's faulty or because of artificial restrictions like leased/licensed hardware) or systems that support "hot-plugging" CPUs, had new CPUs added but not yet enabled.

Use lscpu to get mumber of cores per socket; then multiply by the number of sockets;then by threads per core.