1. Application Performance on IBM i

Macro Performance Factors and Micro Performance Factors

Anything that affects the performance on IBM i will usually fall into one of the following categories:

• Macro performance factors: these are factors that each have a very large impact on the way a machine performs.
  
  Some examples of macro performance factors include:

• Interactive vs. Batch job priorities

• Number of batch jobs executing concurrently

• Micro performance factors: these are factors that individually have very small impact on the overall way a machine performs.
  
  Some examples of micro performance factors include:

• Activity levels, pool sizes, etc.

• Number of access paths being maintained

• Number of online users

• Amount of remote communications being performed

Generally speaking, if you have badly set macro performance factors, your machine will run very badly - but it can be easily and cheaply changed to run much better.

Changes made to an individual macro performance factor will usually produce a large and immediate improvement.

With micro performance factors the reverse is often true. If you have a lot of badly set micro performance factors, they will tend to "accumulate", causing your machine to run badly. It may be very difficult and/or expensive to change these factors to improve your machine performance.

Changes made to an individual micro performance factor will often produce only very slight improvements in performance.

Also see

1.1 Interactive, Batch and Overnight Processing 1.2 Using Working Lists and the KEEP_LAST Parameter 1.3 Keeping Heavily Used Files Open 1.4 Using the OPEN Command Instead of a Logical View to Order Data

1.5 Other File Opening Considerations 1.6 Clean Up Considerations for Heavy Usage Functions 1.7 People and Machine Performance - Some Things to Consider