The performance-tuning process

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Performance tuning is primarily a matter of resource management and correct system-parameter setting.

Tuning the workload and the system for efficient resource use consists of the following steps:

  1. Identifying the workloads on the system
  2. Setting objectives:
    1. Determining how the results will be measured
    2. Quantifying and prioritizing the objectives
  3. Identifying the critical resources that limit the system's performance
  4. Minimizing the workload's critical-resource requirements:
    1. Using the most appropriate resource, if there is a choice
    2. Reducing the critical-resource requirements of individual programs or system functions
    3. Structuring for parallel resource use
  5. Modifying the allocation of resources to reflect priorities
    1. Changing the priority or resource limits of individual programs
    2. Changing the settings of system resource-management parameters
  6. Repeating steps 3 through 5 until objectives are met (or resources are saturated)
  7. Applying additional resources, if necessary

There are appropriate tools for each phase of system performance management (see Monitoring and tuning commands and subroutines). Some of the tools are available from IBM®; others are the products of third parties. The following figure illustrates the phases of performance management in a simple LAN environment.

Figure 1. Performance Phases. The figure uses five weighted circles to illustrate the steps of performance tuning a system; plan, install, monitor, tune, and expand. Each circle represents the system in various states of performance; idle, unbalanced, balanced, and overloaded. Essentially, you expand a system that is overloaded, tune a system until it is balanced, monitor an unbalanced system and install for more resources when an expansion is necessary.
Performance Phases