I have a 4X Xeon X7560 Dell r810 server that uses a lot of energy, even while idle (400 watts). I don't need all 4 CPUs active when the server is idle or under light load, so I wonder if I can save energy by disabling them.
I know you can dynamically disable logical cores ("processors" as Linux calls them) with
echo 0 > /sys/devices/system/cpu/cpu[number]/online, but how can I disable an entire CPU socket while the system is running in a way that will prevent that CPU from consuming energy? And I also need to be able to re-enable them without rebooting. I tried disabling all lcores that were mapped to a socket, and I didn't see any change in idle power consumption.