11.1 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.