How to count the number of CPU cores

cpu

Of course we know cat /proc/cpuinfo |grep "cpu cores" will give an output

[root@14:47 ~]#  cat /proc/cpuinfo |grep "cpu cores"
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2

But actually I want to get the total number of cpu cores. I want the result to be

cpu cores: 8

How can I get such a result?

Best Answer

If you are only interested in the sum, you can also use GNU awk:

cat /proc/cpuinfo |grep "cpu cores" | awk -F: '{ num+=$2 } END{ print "cpu cores", num }'

Edit: This is the correct answer for the OP's intention to sum the numbers of the last column. However the question about finding out how many cores (physical/virtual) are on the machine is given in the other answers to the question.

Related Solutions

Linux – How to have 400% CPU occupied on 2 cores

Two dual-core processors contain 4 CPUs. Multi-threaded processors also exist. Each thread appears as a CPU to the OS, although they are not true CPUs as are cores. Most usually multi-threaded CPUs have two threads per core, so you can have a single, dual-threaded, dual-core processor that appears to your OS at 4 CPUs.

It should be noted that Sun Microsystems had a T2 chip which had 8 cores and 8 threads per core for 64 virtual CPUs on a single processor.

So what are logical cpu cores (as opposed to physical cpu cores)

Physical cores are just that, physical cores within the CPU. Logical cores are the abilities of a single core to do 2 or more things simultaneously. This grew out of the early Pentium 4 CPUs ability to do what was termed Hyper Threading (HTT).

It was a bit of a game that was being played where sub components of the core weren't being used for certain types of instructions while, another long running instruction might have been being executed. So the CPU could in effect work on 2 things simultaneously.

Newer cores are more full-fledged CPUs so they're working on multiple things simultaneously, but they aren't true CPUs as the physical cores are. You can read more about the limitations of the hyperthreading functionality vs. the physical capabilities of the core here on tomshardware in this article titled: Intel Core i5 And Core i7: Intel’s Mainstream Magnum Opus.

You can see the breakdown of your box using the lscpu command:

$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
CPU(s):                4
Thread(s) per core:    2
Core(s) per socket:    2
CPU socket(s):         1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 37
Stepping:              5
CPU MHz:               2667.000
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3

In the above my Intel i5 laptop has 4 "CPUs" in total

CPU(s): 4

of which there are 2 physical cores (1 socket × 2 cores/socket = 2 cores)

Core(s) per socket: 2

CPU socket(s): 1

of which each can run up to 2 threads

Thread(s) per core: 2

at the same time. These threads are the core's logical capabilities.

Best Answer

Related Solutions

Linux – How to have 400% CPU occupied on 2 cores

So what are logical cpu cores (as opposed to physical cpu cores)

Related Question