I have a dual boot MacBook (late 2008) with Mac OS 10.9 and NixOS. I observe that under similar conditions, with only one or two applications open and not doing any computations, the CPU gets 5-10 °C hotter under NixOS than under Mac OS. This can even be felt on touch.
In my NixOS configuration, i have
powerManagement.enable = true powerManagement.cpuFreqGovernor = "powersave";
Is this a result of some inefficiency of Linux kernel, or am i missing some configuration options under NixOS, or is it a NixOS bug?
This energy consumption problem may be not specific to NixOS and be a general issue with Linux on MacBook, as mentioned in this "Linux on Mac?" reddit thread.
However, this looks strange: I have installed system-monitor GNOME shell extension and could observe that in idle condition the CPU usage is oscillating between 1% and 2%, while the CPU Core temperature still stays above 60 °C (at room temperature of about 25 °C), with the fan doing 2000 rpm.
What could be using so much power while the CPU is only 1-2% used?
This turned out to be related to (the absence of) the proprietary NVidia driver.