The efficiency of sort processing is measured in terms of the performance measures of CPU time, elapsed time, and I/O activity. Ordinarily, when MFX performs a sort, it seeks to balance these performance measures in a way that yields the best overall sort performance. It is possible, however, to define a particular performance measure as more important than others for a particular job.
This can be done through MFX’s Dynamic Storage Management (DSM) facility, which makes available four optimization modes for sort processing. These are BALANCE, CPU, ELAP and IO. BALANCE is the default optimization mode which provides the best overall balance between CPU time, sort elapsed time and I/O activity to SORTIN, SORTOUT and SORTWK.
If CPU time is given the highest priority, MFX will minimize this resource at the expense of elapsed time and I/O activity. Selecting ELAP as the optimization mode will cause MFX to minimize the elapsed (wall clock) time of each sort, usually at some expense of the sort’s CPU time. Likewise, if IO is selected as the optimization mode, MFX will minimize the I/O activity (EXCPs) performed by the sorts.