Adjusting Your Process Priority

Use SET PROCESS/PRIORITY=n, where n is a number between 0 and 15. This sets the base scheduling priority of your process, determining the amount of CPU attention it will receive. Processes with higher priorities are scheduled first. The default scheduling priority for most interactive processes is 4. You must hold the ALTPRI privilege to raise your priority above its default level, although anyone may lower his or her own priority. If you hold ALTPRI, you should nevertheless use caution when raising your priority, and you should never attempt to raise it above 15.

A user may choose to lower his priority if he were about to run a long, CPU-intensive program that might interfere with the CPU response of his other processes or those of other users.

You may also adjust the priority of your batch processes by placing a SET PROCESS /PRIORITY command in your batch command procedures, but this is not necessarily recommended. Batch processes usually have lower base priorities than interactive processes carefully determined by the system manager.

Please note that the system will respond sharply to even small changes in a process priority. Also, increasing the scheduling priority of a process that performs frequent I/O operations or generates large numbers of page faults will not result in as much benefit as one might expect. These processes are constrained by factors other than CPU performance and so will not respond to the same degree as other processes.