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 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.
- Enable hard and soft CPU shares by configuring the wlm_disp_cpu_shares database
manager configuration parameter. See step 1 in: Enabling and setting CPU shares.
- Create or alter a service class and configure a hard or soft CPU
share by using the CREATE SERVICE CLASS or ALTER SERVICE CLASS statement.
See: Enabling and setting CPU shares.
- Set the minimum CPU utilization percentage for the workload management
dispatcher to consider service classes to be active by configuring
the wlm_disp_min_util database manager configuration
parameter. See: Setting minimum CPU resource utilization for service class to be considered active.
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
DB2 10.5 for Linux, UNIX, and Windows