https://github.com/tklauser/numcpus

Go package providing information about the number of CPUs in the system
https://github.com/tklauser/numcpus

bsd cpu cputopology go golang linux numa offline online unix

Last synced: 3 days ago
JSON representation

Go package providing information about the number of CPUs in the system

• Host: GitHub
• URL: https://github.com/tklauser/numcpus
• Owner: tklauser
• License: apache-2.0
• Created: 2018-12-13T16:31:43.000Z (about 6 years ago)
• Default Branch: main
• Last Pushed: 2025-01-21T10:08:13.000Z (16 days ago)
• Last Synced: 2025-01-25T23:41:12.139Z (12 days ago)
• Topics: bsd, cpu, cputopology, go, golang, linux, numa, offline, online, unix
• Language: Go
• Homepage: https://pkg.go.dev/github.com/tklauser/numcpus
• Size: 1.03 MB
• Stars: 26
• Watchers: 3
• Forks: 10
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# numcpus

[![Go Reference](https://pkg.go.dev/badge/github.com/tklauser/numcpus.svg)](https://pkg.go.dev/github.com/tklauser/numcpus)

[![GitHub Action Status](https://github.com/tklauser/numcpus/workflows/Tests/badge.svg)](https://github.com/tklauser/numcpus/actions?query=workflow%3ATests)

Package numcpus provides information about the number of CPUs in the system.

It gets the number of CPUs (online, offline, present, possible, configured or

kernel maximum) on Linux, Darwin, FreeBSD, NetBSD, OpenBSD, DragonflyBSD or

Solaris/Illumos systems.

On Linux, the information is retrieved by reading the corresponding CPU

topology files in `/sys/devices/system/cpu`.

On BSD systems, the information is retrieved using the `hw.ncpu` and

`hw.ncpuonline` sysctls, if supported.

Not all functions are supported on Darwin, FreeBSD, NetBSD, OpenBSD,

DragonflyBSD and Solaris/Illumos. ErrNotSupported is returned in case a

function is not supported on a particular platform.

## Usage

```Go

package main

import (

	"fmt"

	"os"

	"github.com/tklauser/numcpus"

)

func main() {

	online, err := numcpus.GetOnline()

	if err != nil {

		fmt.Fprintf(os.Stderr, "GetOnline: %v\n", err)

	}

	fmt.Printf("online CPUs: %v\n", online)

	possible, err := numcpus.GetPossible()

	if err != nil {

		fmt.Fprintf(os.Stderr, "GetPossible: %v\n", err)

	}

	fmt.Printf("possible CPUs: %v\n", possible)

}

```

## References

* [Linux kernel sysfs documentation for CPU attributes](https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-system-cpu)

* [Linux kernel CPU topology documentation](https://www.kernel.org/doc/Documentation/cputopology.txt)