Or how a host schedules CPU cycles.
So I learnt an interesting tidbit of information the other day to do with a VPS and why it had high load and bugger all CPU usage. If you see something similar to this in top:
top - 20:30:53 up 8 days, 6:42, 1 user, load average: 9.37, 10.81, 9.67 Tasks: 135 total, 12 running, 133 sleeping, 0 stopped, 0 zombie Cpu(s): 30.8%us, 0.8%sy, 0.0%ni, 67.8%id, 0.5%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 3790268k total, 3621780k used, 168488k free, 350528k buffers Swap: 1830908k total, 11464k used, 1819444k free, 2753548k cached
over a long period of time, and you have more than 2 CPUs in your VPS – consider dropping back to 2 vCPU’s.
But Why? Surely 4 CPUs is Better than 2!
They certainly are, but when the underlying host gets busy, slots for 2 vCPU hosts get scheduled a lot more often than slots for quad vCPU’s – this is all down to the scheduler.