Setting dispatch concurrency level

Set the dispatch concurrency level by setting the value of the wlm_disp_concur database manager configuration parameter to COMPUTED or a manually-set value. You set the dispatch concurrency level to an optimal value that ensures maximum efficiency and that gives the workload management dispatcher maximum control over CPU resource allocations.

Procedure

To set the dispatch concurrency level:

Using the command line processor (CLP), issue the UPDATE DATABASE MANAGER CONFIGURATION (or UPDATE DBM CFG) command and set the value of the wlm_disp_concur database manager configuration parameter to one of the following possibilities:
  • COMPUTED (default)
  • manually_set_value
The following example manually sets the dispatch concurrency level to 16, which is 4 times the 4 CPUs available on the system, and is updated immediately by first attaching to your Db2® instance:
attach to instance-name
update dbm cfg using wlm_disp_concur 16
detach

Results

The dispatch concurrency level has been set. If set to COMPUTED, the concurrency level is determined by the Db2 database manager. If manually set, you might need to tune the concurrency level to an optimal value that ensures maximum efficiency and that gives the workload management dispatcher maximum control over CPU resource allocations.

What to do next

After having set the dispatch concurrency level, consider completing the following tasks:
  • For the dispatch concurrency level setting to be effective, you must enable the workload management dispatcher by configuring the wlm_dispatcher database manager configuration parameter. See: Enabling the workload management dispatcher.
  • Create or alter a service class and configure the CPU limit by using the CREATE SERVICE CLASS or ALTER SERVICE CLASS statement. See: Setting a CPU limit.

After the workload management dispatcher has been enabled and the dispatch concurrency level has been set, monitor your system for a drop in throughput and CPU utilization. If a drop in either metric does occur, increase the value of the wlm_disp_concur configuration parameter in increments of the number of available processors. For more information about monitoring and tuning workload management dispatcher performance, see: Monitoring and tuning workload management dispatcher performance