Program Execution Priority -- Priority and Nice values

Program Execution Priority-Priority and Nice value 1. Relational concept: Priority is the PRI value. The core control of this value can be changed for Nice that cannot be changed. Relationships: PRI (new) = PRI (old) + nice www.2cto.com 2. Nice adjustment restrictions: nice value can be adjusted from-20 ~ 19; root can adjust the Nice value of programs of himself or others at will, and the value range is-20 ~ 19; Generally, users can only adjust their own program Nice value, and the range is only 0 ~ 19 (to avoid general users from occupying system resources); general users can only adjust the nice value to a higher value. For example, if nice is 5, it can only be adjusted to 5 in the future; 3. Adjustment Method 1: The newly executed command gives the new nice value [root @ www ~] # Nice [-n number] command Option and parameter:-n: Followed by a value. The value range is-20 ~ 19. If www.2cto.com is checked with ps-l, the displayed PRI is PRI (new), and the core is automatically adjusted, not the PRI (old) + nice value, will increase a little. 4. Adjustment Method 2: nice of the existing program re-adjusted renice [number] PID 5. Adjustment Method 3: top