Implement Mhz to current, min and max.

[alexwbaule]

Implement of #1516

Please, is my first PR here, and i only have Linux to test it.

[shirou]

Thank you for your contribution. However, unfortunately, this PR breaks current compatibility. So we cannot accept while in current major version, v3. I have added v4 label, but v4 release date is not discussed yet.

[alexwbaule]

Hi @shirou , can we merge this ?

[shirou]

As I commented, this PR breaks current compatibility. So we cannot merge until v4 is released.

[kkartaltepe]

It seems the current version is v4 now can this be considered again? I was also interested in this data.

--- Edit

And if it does get picked back up a fallback to scaling_cur_freq should be added to support amd-pstate's governor which only reports frequency from there https://docs.kernel.org/admin-guide/pm/amd-pstate.html#key-governors-support (I don't know which is more correct on other platforms/configurations but amd-pstate doesnt report cpuinfo_cur_freq at all).

[alexwbaule]

@shirou , need something to merge ?

[renard]

@alexwbaule I +1 this feature because it eases the ability to figure out any glitches during a benchmark. However I'd recommend to keep a flat structure such as:

MhzCurrent float64 `json:"mhz_current"`
MhzMin float64 `json:"mhz_min"`
MhzMax float64 `json:"mhz_max"`

instead of using a MHz structure.

So far no other collected metric use any sub-structure. It would be better IMHO to keep it that way.

[ccoVeille]

It's a breaking change but why not

[ccoVeille]

I would use MHz

And while you are changing the type and so the output format, I would change the Mhz variable name in the struct

But here,I'm only a random Gopher.

The maintainers of this project might have another opinion

[ccoVeille]

At some point if it's for test purpose that you are resetting it

[ccoVeille]

Please consider writing this

Suggested change

	c.Mhz.Current = float64(u32)
	c.Mhz.Min = 0
	c.Mhz.Max = 0
	c.Mhz = Mhz{Current: float64(u32)}

Abd everywhere you did the replacement

[ccoVeille]

I would pass

Suggested change

	c.Mhz.Current = fillMhz(ctx, "cur", c)
	c.Mhz.Min = fillMhz(ctx, "min", c)
	c.Mhz.Max = fillMhz(ctx, "max", c)
	c.Mhz.Current = fillMhz(ctx, "cpuinfo_cur_freq", c)
	c.Mhz.Min = fillMhz(ctx, "cpuinfo_min_freq", c)
	c.Mhz.Max = fillMhz(ctx, "cpuinfo_max_freq", c)

And then I would use

Suggested change

	c.Mhz.Current = fillMhz(ctx, "cur", c)
	c.Mhz.Min = fillMhz(ctx, "min", c)
	c.Mhz.Max = fillMhz(ctx, "max", c)
	c.Mhz = Mhz{Current: fillMhz(ctx, "cpuinfo_cur_freq", c), Min: fillMhz(ctx, "cpuinfo_min_freq", c), Max: fillMhz(ctx, "cpuinfo_max_freq", c)}

[ccoVeille]

Add a switch here and return 0 if the value are not the one you expect