Adjusting the Execution Priority of Work Processes (System i) 
You have two options for adjusting the priority for executing work processes:
By adjusting the priority in the job description (JOBD)
By using the new, relative priority classes
The priority specified in JOBD must be between 15 and 80. If this is not the case, a warning is given and the priority is JOBD is set to 20 (for priority <15) or to 80 (for priority >80).
You can improve the adjustment of the job priority by using the new job priority classes. There are four relative priority classes that are based on the priority defined in JOBD.
Priority class ID |
Priority in relation to the value in JOBD |
Meaning |
|---|---|---|
HH |
JOBD value - 10 |
Highest priority |
H |
JOBD value - 5 |
Highest priority |
M |
JOBD value - 10 |
Medium priority |
L |
JOBD value +5 |
Low priority |
Before you can use the new priority classes, you must activate the system value QDYNPTYSCD (Dynamic Priority Scheduler) by setting the value to 1. You require a system IPL (initial program load) to make the changes take effect.
You can then specify priority classes for the processes Update (UPD), Batch (BTC), and Spool (SPO). All the other processes have a fixed relative priority. The critical processes Message Server (MS), Dispatcher (DISP), Enqueue (ENQ) and Gateway (GW) are assigned priority class HH, for example. The user cannot change this. The following table displays which type of priority classes are permitted for which work processes. The work processes in bold can be changed by the user.
Priority class ID |
Work process |
|---|---|
HH |
MS, DISP, GW, ENQ |
H |
UPD |
M |
UDP, DIA, UPD2, BTC, SPO |
L |
BTC, SPO |
Transaction RZ11 lets you adjust the priority for the UPD, BTC, or SPO processes. The following parameters are relevant:
Parameters |
Meaning |
|---|---|
Parameter rdisp/prio/upd |
Priority class for UPD |
rdisp/prio/btc |
Priority class for BTC |
rdisp/prio/spo |
Priority class for SPO |
These parameters have M as the default value.
Example
You have activated the new priority classes. Your job description (JOBD) displays a priority of 20. Set UPD to priority class H, BTC to priority class M, and SPO to priority class L. The actual priorities for the various work processes are as follows:
Work process |
Priority of Execution |
|---|---|
MS, DISP, GW, ENQ |
10 |
UPD |
15 |
BTC, DIA, UPD2 |
20 |
SPO |
25 |
If QDYNPTYSCD = 0, all the processes have the default value for the priority of execution that is set in JOBD.
If QDYNPTYSCD = 1, new priority classes are always activated. If an incorrect class was specified for a changeable work process, its default value is assigned to this process and a warning is given.