What does 'nice' mean on CPU utilization graphs?

Question

On Ubuntu server load graphs I see 4 types of CPU consumption: User, System, Nice and Idle.

What does Nice type mean?

Answer 1

It is the CPU scheduling priority, higher vales (+19) mean lower priority, and lower values (-20) mean higher priority (inverse relationship). man 2 getpriority will give you lots of details. You can set the nice value when launching a process with the nice command and then change it with the renice command. Only the superuser can specifiy a priority increase of a process.

Answer 2

On a CPU utilization graph or report, the "nice" CPU percentage is the % of CPU time occupied by processes with a positive nice value (lower scheduling priority -- see man nice for details).

Basically it's CPU time that's currently "in use", but if a normal (nice value 0) or high-priority (negative nice value) process comes along those programs will be kicked off the CPU.

Answer 3

Nice is intended for batch or background jobs. Jobs are niced (given lower scheduling priority) so they don't use CPU when online users could be using it. The nice and renice programs set the nice priority. Negative nice priorities are bad (real-time).

If your have low idle time but a lot of nice time, then you are likely running a background process like Seti at Home or something else similar.