Supported Platforms

Joular Energy Meter runs on Linux, Windows, macOS and FreeBSD, and reads:

The hardware is read by our Joular Core library, the same way as in PowerJoular:

• Intel and AMD processors through RAPL: the powercap files on Linux, the Energy Meter Interface (Windows 11), PawnIO or Hubblo’s driver on Windows, and the cpuctl driver on FreeBSD.
• Macs through powermetrics, installed with macOS. Apple Silicon gives the CPU and the GPU of the chip, Intel Macs the CPU only.
• Raspberry Pi through our regression power models.
• Nvidia cards through NVML (installed with the driver), and AMD cards through the amdgpu hwmon files on Linux and ADLX on Windows.

The CPU usage of the machine, of a process and of an application is read by our CPU Load library.

Whole machine means the processor and the graphics card only. The screen, memory, disks and the losses of the power supply are not measured, so the computer draws more at the plug. A power meter at the plug can be added for that (see Idle Power and Plug Meter).

Required privileges

The CPU load is always read, but the CPU power needs some rights on most systems. When they are missing, a notice says what to do: on Linux, macOS and Windows, with a button that asks the system for the administrator (through the system’s own dialog, never a password field of ours), and on Linux, macOS and FreeBSD, with a button to copy the command instead.

• Linux: the RAPL files are readable by root only (CVE-2020-8694). Allow reading power asks for the administrator through polkit (pkexec), and makes the processor’s counters readable by every user of the machine until the next boot. The application itself keeps running as you. The same by hand, after each boot: sudo chmod -R a+r /sys/class/powercap/intel-rapl. Or start the application with sudo, under X11 (not Wayland).
• Windows: nothing to do on Windows 11. On older versions, install the PawnIO driver, then Restart as administrator (UAC asks), or install Hubblo’s RAPL driver, which needs no administrator.
• macOS: powermetrics needs root. Restart with admin rights asks for your password in macOS’s dialog, then starts the application again as root, with your files and settings still yours. Or from Terminal: sudo "/Applications/Joular Energy Meter.app/Contents/MacOS/joularenergymeter".
• FreeBSD: load the cpuctl driver (sudo kldload cpuctl, or cpuctl_load="YES" in /boot/loader.conf), and start the application with sudo under X11. The kmem group also works, but it can read all memory through /dev/mem.
• Nvidia and AMD graphics cards, and Raspberry Pi, need nothing.

On Windows and macOS, following a process of another user also needs the administrator.