[doc] Provide commands to check rapl support

[arthurzenika]

Bug description

It can be difficult to detect that scaphandre is not support on the server's CPU

To Reproduce

root@host:~# modprobe intel_rapl
modprobe: FATAL: Module intel_rapl not found in directory /lib/modules/5.10.0-9-amd64
root@host:~# modprobe intel_rapl_common
modprobe: ERROR: could not insert 'intel_rapl_common': No such device
root@host:~# insmod /lib/modules/5.10.0-9-amd64/kernel/drivers/powercap/intel_rapl_common.ko
insmod: ERROR: could not insert module /lib/modules/5.10.0-9-amd64/kernel/drivers/powercap/intel_rapl_common.ko: No such device
root@host:~# dmesg | grep rapl
[2424208.753699] intel_rapl_common: driver does not support CPU family 6 model 26
[2481103.619707] intel_rapl_common: driver does not support CPU family 6 model 26

Expected behavior

A bit more warning in the documentation about supported/unsupported CPUs

I ended up reading https://hubblo-org.github.io/scaphandre-documentation/compatibility.html and https://hubblo-org.github.io/scaphandre-documentation/references/sensor-powercap_rapl.html which mentions the age of the CPU. Maybe there could be a command dmesg | grep rapl or some flag in /proc/cpuinfo ?

Maybe there could be some sort of detection in the binary to guide the end user to this conclusion ?

Environment

• Linux distribution version : debian bullseye/buster [e.g. Ubuntu 20.04.1]
• Kernel version (output of uname -r) : 5.10.0-9-amd64

[bpetit]

Hi @arthurzenika !

How about this ?

• checking-rapl-is-available-on-your-cpu
• rapl-domains

[arthurzenika]

Awesome, thanks !