cpu: add frequency support for apple silicon m1/m2 cpus

[shoenig]

This PR adds support for reading the frequency of Apple Silicon M1/M2 CPUs. We do so by reading the values out of the IOKit framework, as a few other projects have now demonstrated to be possible. This requires the use of CGO. The library provides a convenience IsAppleSilicon() guard to detect whether the values can be read.

Currently gopsutil does not support the big.LITTLE CPU architectures (i think?) - in fact the P and E cores have different max frequencies. For now, just read the P core frequency. The E core data is readily available if we want to read it in the future.

Closes #1000

Small example program

package main

import (
        "fmt"

        "github.com/shoenig/go-m1cpu"

        "github.com/shirou/gopsutil/v3/cpu"
)

func main() {
        fmt.Println("is Apple Silicon:", m1cpu.IsAppleSilicon())
        fmt.Println("model name", m1cpu.ModelName())
        fmt.Println("pCore GHz", m1cpu.PCoreGHz())
        fmt.Println("eCore GHz", m1cpu.ECoreGHz())
        fmt.Println("pCore Hz", m1cpu.PCoreHz())
        fmt.Println("eCore Hz", m1cpu.ECoreHz())

        fmt.Println("----- gopsutil ----")

        infos, err := cpu.Info()
        if err != nil {
                panic(err)
        }

        for _, info := range infos {
                fmt.Println("info.Mhz", info.Mhz)
        }
}

go run main.go
is Apple Silicon: true
model name Apple M2 Pro
pCore GHz 3.504
eCore GHz 2.424
pCore Hz 3504000000
eCore Hz 2424000000
----- gopsutil ----
info.Mhz 3.504e+09

[shirou]

Excellent! This PR is very promising.

However, could you please fix the following?

• Create a new cpu_darwin_test.go and move all darwin tests there to fix the lint issue.
• use strncmp instead of strcmp.

[shoenig]

For strncmp I merged https://github.com/shoenig/go-m1cpu/pull/3/files and bumped the version here.

And I created cpu_darwin_test.go and added a specific Test_CpuInfo_AppleSilicon test case.

Let me know if there's anything else to do ~

EDIT: oof, I realized I was setting the Mhz field with Hz ... fixed that bug and expanded to the test case to check for such an absurd value.

[shirou]

Awesome! This PR is probably the PR that many people have been waiting for! Great thanks!