Slot Occupancy

What does this counter show?

The percentage of time where the USC looked for a slot that is ready to run and found one.

What does a high value mean?

A high value means that the USC is never starved; it always has something that can run.

A low value means that either there is no work to do, or that there is work to do but it is being stalled.

If this value is low at times when it should be high, check the Register Overload counter. It may be that additional slots are not ready to run, because running slots are using too many registers.