In order to ensure efficient CPU utilization in a UDS/SQL configuration, it is essential that the correct BS2000 settings be used. These settings are described below.
Task priorities
BS2000 offers a priority facility to control system behavior in peak and overload situations (see the manual "Introduction to System Administration" for details).
The best method of ensuring guaranteed behavior for server tasks over an extended period is to use fixed priorities for peak-load requirements. The permanent prioritization of server tasks achieved by this method could, however, have a negative impact on other tasks of the same category.
Some settings of load parameters are only meaningful in combination with fixed priorities.
The effect of various settings are explained in section “Example of a peak-load configuration”.
Task attribute TP
UDS/SQL switches every server task to the BS2000 task attribute TP, which enables continuous utilization of processors by server tasks. Note, however, that the job class which uses the server tasks must be assigned to the task category TP (see the job class assignment on "Starting DBH").
The BS2000 command SHOW-JOB-CLASS can be used to verify whether the task category TP has been assigned for the job class. The job class assignment can be checked with the BS2000 command SHOW-USER-STATUS,INFORMATION=*JOB.
The BS2000 subsystem TANGRAM
BS2000 users can use the performance-enhancing subsystem TANGRAM (Task and Group Affinity Management) for multiprocessors (see the manual "Introduction to System Administration"). No special UDS/SQL setting is required by the database administrator for this purpose; UDS/SQL automatically reports all server tasks in a task group to TANGRAM.
TANGRAM can improve overall performance especially in cases involving UDS/SQL configurations for which the load parameter PP SERVERTASK must be set to a medium or high value, either due to strongly fluctuating loads or due to the load parameter PP IO=SYNC or in cases when no prioritization is possible due to other important applications.
By contrast, no significant improvement can be expected for UDS/SQL configurations that have been optimally set by other methods (fixed BS2000 priorities, UDS/SQL load parameters). TANGRAM can, however, also be used in these cases to optimize other multitask systems (e.g. openUTM) without damaging side-effects on the UDS/SQL configuration.