DB2 10.5 for Linux, UNIX, and Windows

Workload management dispatcher overview

The DB2® workload management dispatcher is a built-in DB2 technology by which you can specifically allocate CPU resources to work that is being executed on a database server. CPU resource entitlements can be controlled by using CPU shares and CPU limit attributes on DB2 service classes.

Overview

Particularly useful under workload conditions that strain the system CPU resources, the dispatcher can effectively manage service class CPU resource entitlements with attributes such as the uncapped (almost unrestricted) soft CPU shares, and the two capped (limited) attributes: hard CPU shares and CPU limits. You can use the uncapped soft CPU shares to give high-priority-work service classes any unused CPU resources. In addition, you can enforce controls on the CPU resource entitlements by using capped hard CPU shares or CPU limits assigned to low-priority-work service classes, thereby limiting their impact on high-priority work. Under conditions where the system CPU resources are less strained, you can use one or both of the capped attributes, without the need to assign uncapped attributes, to effectively control the CPU resource entitlements between service classes running in a typical, underrun-CPU environment.

The workload management dispatcher infrastructure operates at the instance level in the DB2 database manager. The dispatcher operates by limiting the number of executing agents to be dispatched to the operating system (OS) and how long each agent is allowed to execute, at any given time. The number of executing agents that can be dispatched at the same time is referred to as the dispatch concurrency level.

The DB2 workload management dispatcher has the following benefits:
  • Easy to implement, requiring less time and effort than implementing an OS WLM such as AIX® WLM or Linux WLM.
  • Supports flexible CPU allocation throughout the normal daily ebb and flow of system use. This flexibility is accomplished through the provisioning of both permanent allocations that are enforced all the time (hard CPU shares and CPU limits), or dynamic allocations that are enforced only when demand exceeds capacity (soft CPU shares).
  • Self-contained within the DB2 database manager such that setting CPU resource entitlements provides you with workload control that is effective across all platforms due to its independence from an OS WLM such as AIX WLM or Linux WLM.
  • You can continue to use the OS WLM products as a workload control mechanism, but it is not necessary if the extra implementation complexity (for example, setting up AIX WLM on each member) or if the organizational strife (for example, system administrator reluctance to implement or permit use of OS WLM) is a barrier. Alternatively, you can use the OS WLM products for monitoring purposes while relying on the DB2 workload management dispatcher for workload control.