Linux get cpu cores count

How to check how many CPUs are there in Linux system

I am a new Linux user. How do you check how many CPUs are there in Linux system using the command line option?

Introduction: One can obtain the number of CPUs or cores in Linux from the command line. The /proc/cpuinfo file stores CPU and system architecture dependent items, for each supported architecture. You can view /proc/cpuinfo with the help of cat command or grep command/egrep command. This page shows how to use /proc/cpuinfo file and lscpu command to display number of processors on Linux.

Tutorial details
Difficulty level	Easy
Root privileges	Yes
Requirements	None
Est. reading time	3 minutes

How do you check how many CPUs are there in Linux system?

You can use one of the following command to find the number of physical CPU cores including all cores on Linux:

1. lscpu command
2. cat /proc/cpuinfo
3. top or htop command
4. nproc command
5. hwinfo command
6. dmidecode -t processor command
7. getconf _NPROCESSORS_ONLN command

Let us see all commands and examples in details.

How to display information about the CPU on Linux

Just run the lscpu command:
$ lscpu
$ lscpu | egrep ‘Model name|Socket|Thread|NUMA|CPU\(s\)’
$ lscpu -p

The output clearly indicate that I have:

1. CPU model/make: AMD Ryzen 7 1700 Eight-Core Processor
2. Socket: Single (1)
3. CPU Core: 8
4. Thread per core: 2
5. Total threads: 16 ( CPU core[8] * Thread per core [2])

Use /proc/cpuinfo to find out how many CPUs are there in Linux

Run top or htop command to obtain the number of CPUs/cores in Linux

Execute nproc print the number of CPUs available on Linux

Let us print the number of installed processors on your system i.e core count:
$ nproc —all
$ echo «Threads/core: $(nproc —all)»
Sample outputs:

How to probe for CPU/core on Linux using hwinfo command

$ hwinfo —cpu —short ## short info ##
$ hwinfo —cpu ## detailed info on CPUs ##

Linux display CPU core with getconf _NPROCESSORS_ONLN command

One can query Linux system configuration variables with getconf command:
$ getconf _NPROCESSORS_ONLN
$ echo «Number of CPU/cores online at $HOSTNAME: $(getconf _NPROCESSORS_ONLN)»
Sample outputs:

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dmidecode -t processor command

You can use get BIOS and hardware information with dmidecode command (DMI table decoder) on Linux. To find out how many CPUs are there in Linux system, run:
$ sudo dmidecode -t 4
$ sudo dmidecode -t 4 | egrep -i ‘core (count|enabled)|thread count|Version’

Here is a quick video demo of lscpu and other commands:

Conclusion

You learned how to display information about the CPU architecture, core, threads, CPU version/model, vendor and other information using various Linux command line options.

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Linux: Find Number of CPU Cores Command

H ow do I find out the number of CPU cores available under HP x86_64 Linux serer running on RHEL / Debian Linux 6.x?

You can use the lscpu or nproc command to display the number of processing units available to the current process, which may be less than the number of online processors (please note that not all server supports hotplug a CPU on a running Linux system).[donotprint]

Tutorial details
Difficulty level	Easy
Root privileges	No
Requirements	None
Est. reading time	1m

[/donotprint]

The proc file system is a pseudo-file system which is used as an interface to kernel data structures. It is commonly mounted at /proc. The /proc/cpuinfo file is nothing but a collection of CPU and system architecture dependent items, for each supported architecture a different list. Two common entries are processor which gives CPU number and bogomips; a system constant that is calculated during kernel initialization. SMP machines have information for each CPU.

nproc Example

The nproc command shows the number of processing units available:
# nproc
Sample outputs:

lscpu Command

lscpu gathers CPU architecture information form /proc/cpuinfon in human-read-able format:
# lscpu
Sample outputs:

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/proc/cpuinfo

The /proc/cpuinfo and sysfs stores info about your CPU architecture ike number of CPUs, threads, cores, sockets, NUMA nodes, information about CPU caches, CPU family, model, bogoMIPS, yte order and much more:
# less /proc/cpuinfo

Check out related media

Here is a quick demo of lscpu and /proc/cpuinfo commands:

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14 Methods to check the number of CPUs in Linux

All Linux systems run on multi-core CPU processors, but many of us are confused to find or understand CPU, cores, and Threads information.

Hope this article helps you understand exactly what it is.

What’s a CPU Socket?

A CPU socket or CPU slot is a connector on the motherboard that allows a computer processor to connect to the motherboard. This is called a physical CPU (central processing unit).

What is the CPU Core?

Initially, CPUs use to come with single core, but manufacturers added more cores to increase performance, which is why the core came into the picture.

For example, a dual-core CPU has two central processing units, so it appears to be two CPUs per operating system.

Similarly, a quad core CPU has four central processing units and an octa core CPU has eight central processing units.

What is CPU Thread?

Intel’s hyper-threading technology makes it possible to use processor resources more efficiently by running multiple threads in each core (each core has two threads).

This improves processor throughput and improves overall performance in threaded software.

See the following details for better understanding of this in real-time. This is the sample data I took from my system.

A physical CPU (1), which has 4 CPU cores, and has 2 threads in each core.

The calculation is below: CPUs = Threads Per Core X Number of cores per socket X Number of CPU (Sockets) .

Output: 2 x 4 x 1 = 8

Method-1: How to find the number Of CPUs on Linux using the “/proc/cpuinfo” file

The “/proc/cpuinfo” file is a virtual text file that contains information about CPUs (central processing units) on a computer.

It contains useful information like CPU architecture, vendor name, model name. You can only get a number of CPUs by using the grep command as follows.

To view detailed information about the CPU, run the following command.

Method-2: How to check the number of CPUs on Linux using the nproc Command

It prints the number of processing units available for the current process. It is part of the GNU Coreutils package, which is installed by default on most Linux systems.

Method-3: How to find the number of CPUs on Linux using the lscpu Command

The lscpu command displays information about the CPU architecture, which is collected from the sysfs and the /proc/cpuinfo file.

The information includes, number of CPUs, threads, cores, sockets, NUMA nodes, CPU caches, CPU family and model, which print infomration in human readable format.

Alternately use the lscpu command to print only number of processor.

Method-4: How to check the number of CPUs on Linux using the getconf Command

getconf stands for get configuration values. getconf utility used to write the value of the variable specified by the system_var & path_var operand. The value of each configuration variable were obtained from IEEE Std 1003.1-2001

Method-5: How to find the number of CPUs on Linux using the dmidecode Command

Dmidecode is a tool which reads a computer’s DMI (stands for Desktop Management Interface) (some say SMBIOS – stands for System Management BIOS) table contents and display system hardware information in a human-readable format.

This table contains a description of the system’s hardware components, as well as other useful information such as serial number, Manufacturer information, Release Date, and BIOS revision, etc.

Total CPUs = CPU1 Thread Count
8=8

Method-6: How to check the number of CPUs on Linux using the inxi Command

inxi command is a nifty tool for verifying hardware information on Linux, and offers a wide range of options to get all the hardware information on a Linux system, which I haven’t seen in any other application available on Linux.

It shows system hardware, CPU, drivers, Xorg, Desktop, Kernel, gcc version(s), Processes, RAM usage, and a wide variety of other useful information.

Totally 8 CPUs are listed above

Method-7: How to find the number of CPUs on Linux using the hwinfo Command

The hwinfo command is a hardware information tool that is used to analyze the hardware on a computer and to display detailed information about the variety of hardware components in a human readable format.

It reports information about CPU, RAM, keyboard, mouse, graphics card, sound, storage, network interface, disk, partition, bios, and bridge, etc.

A total of 8 CPUs are listed above

Method-8: How to check the number of CPUs on Linux using the top Command

The top command provides a dynamic real-time view of the running system processes and a list of tasks currently managed by the Linux kernel.

By default, the top command displays the average of output for all CPUs, and if you want to print everything separately to the top command output, press 1 “number one” when running the top application.

Method-9: How to find the number of CPUs on Linux using the htop Command

The Htop command is an open source ncurses-based process viewer for Linux. This is similar to the top command, but allows you to scroll vertically and horizontally, so you can see all the processes running the system with their entire command line.

Process-related tasks (Killing, renicing) can be performed without entering their PIDs.

Method-10: How to check the number of CPUs on Linux using the CorFreq Command

CoreFreq is a CPU monitoring software designed for Intel 64-bits processors and supported architectures such as Atom, Core 2, Nehalem, SandyBridge and superior, AMD Family 0F.

CoreFreq provides a framework for retrieving CPU data with a high degree of accuracy. By default the corefreq output displays the number of CUP cores in the system.

Method-11: How to find the number of CPUs on Linux using the “/sys/devices/system/cpu/” file

Alternatively, you can get a processor information from the “/sys/devices/system/cpu/” file. It is a set of global and unique CPU attributes. Individual CPU attributes are in subdirectories named by the kernel’s logical CPU number.

• online: cpus that are online and being scheduled.
• possible: cpus that have been allocated resources and can be brought online if they are present.
• present: cpus that have been identified as being present in the system.

Method-12: How to find the number of CPUs on Linux using the “/proc/interrupts” File

This file contains information about how many times “/proc/interrupts” interrupts the processor.

Method-13: How to find number of CPUs on Linux using the Python multiprocessing.cpu_count() method

You can count the number of cores in the system using python multiprocessing.cpu_count() method. Alternatively, import the os module using syscall getconf.

Method-14: How to check the number of CPUs on Linux using the Python psutil library

psutil (process and system utilities) is a cross-platform library for retrieving information on running processes and system utilization (CPU, memory, disks, network, sensors) in Python.

It is useful mainly for system monitoring, profiling and limiting process resources and management of running processes. It implements many functionalities offered by classic UNIX command line tools such as ps, top, iotop, lsof, netstat, ifconfig, free and others.

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9 Useful Commands to Get CPU Information on Linux

In a previous article, we put together a list of 10 useful commands to collect system and hardware information in Linux. In this guide, we will narrow down to the CPU/processor, and show you various ways of extracting detailed information about your machine CPU.

Just to give you an overview, we will query information such as CPU architecture, vendor_id, model, model name, number of CPU cores, speed of each core, and lots more.
Essentially, the /proc/cpuinfo contains this all info, every other command/utility gets its output from this file.

With that said, below are 9 commands for getting info about your Linux CPU.

1. Get CPU Info Using cat Command

You can simply view the information of your system CPU by viewing the contents of the /proc/cpuinfo file with the help of cat command as follows:

To get a little specific, you can employ the grep command – a CLI tool for searching plain-text data for lines matching a regular expression. This can help you only output vendor name, model name, number of processors, number of cores, etc:

2. lscpu Command – Shows CPU Architecture Info

The command lscpu prints CPU architecture information from sysfs and /proc/cpuinfo as shown below:

3. cpuid Command – Shows x86 CPU

The command cpuid dumps complete information about the CPU(s) collected from the CPUID instruction, and also discover the exact model of x86 CPU(s) from that information.

Make sure to install it before running it.

Once installed, run cpuid to collect information concerning the x86 CPU.

4. dmidecode Command – Shows Linux Hardware Info

dmidecode is a tool for retrieving hardware information of any Linux system. It dumps a computer’s DMI (a.k.a SMBIOS) table contents in a human-readable format for easy retrieval. The SMBIOS specification defines various DMI types, for CPU, use “processor” as follows:

5. Inxi Tool – Shows Linux System Information

Inxi is a powerful command-line system information script intended for both console and IRC (Internet Relay Chat). You can use it to instantly retrieve hardware information.

You can install like so:

To display complete CPU information, including per CPU clock-speed and CPU max speed (if available), use the -C flag as follows:

6. lshw Tool – List Hardware Configuration

lshw is a minimal tool for gathering in-depth information on the hardware configuration of a computer. You can use the -C option to select the hardware class, CPU in this case:

7. hardinfo – Shows Hardware Info in GTK+ Window

hardinfo displays hardware information in a GTK+ window, you can install it as follows:

Once you have it installed, type:

Linux System Information

It also enables you to generate a system hardware info report by clicking on the “Generate Report” button. From the interface below, click on “Generate” to proceed. Note that you can choose the hardware info category to be generated.

Generate System Information Report

Once you have generated the report in html format, you can view it from a web browser as shown below.

Linux System Detailed Information

8. hwinfo – Shows Present Hardware Info

hwinfo is used to extract info about the hardware present in a Linux system. To display info about your CPU, use the —cpu

9. nproc – Print Number of Processing Units

nproc command is used to show the number of processing unit present on your computer:

For additional usage info and options, read through the man pages of these commands like this:

That’s it for now! You can share with us additional ways of extracting CPU information in Linux via the feedback form below.

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