Surely part of conserving resources is matching your hardware to the load. In the same way you wouldn't reserve a datacenter for a job that can be done on a sin

Surely part of conserving resources is matching your hardware to the load. In the same way you wouldn't reserve a datacenter for a job that can be done on a single machine, you wouldn't reserve a large machine for a single-threaded load. You either pick a smaller, more efficient machine or do more work on that machine. Also if you are single threaded you do not have to race to sleep on all the other cores. They are already sleeping.