Tuning the controller

Performance problems in the controller are most often associated with contention for the current plan enqueue. The amount of time the lock is held by the subtasks is directly related to the amount of work the subtasks must perform. IBM Tivoli Workload Scheduler for z/OS generates messages documenting the usage of the current plan lock when STATMSG(CPLOCK) is defined on the JTOPTS initialization statement.

The subtasks using the current plan lock are:

• The workstation analyzer (WSA) subtask to start operations at computer, WTO, and nonreporting workstations. The WSA also generates alerts when LATEOPER or DURATION is defined on the ALERTS initialization statement.
• The event manager (EM) subtask processes the events sent from the trackers and updates the current plan as appropriate. The event manager also acts on behalf of the restart and cleanup (RC), automatic recovery (AJR), and event-triggered tracking (ETT) functions.
• The general service (GS) subtasks provide the interface between the controller data and the user. It provides service to the ISPF and OS/2 dialog users, API transaction programs, and the program interface. GS is the only current plan lock user who can take the lock shared, for true read-only transactions.
• The normal-mode manager (NMM) subtask is responsible for integrity of the controller data. NMM enqueues the CP lock when current plan or JCL repository backups are required, or when a new current plan (NCP) has been created.