Getting the scheduling error

long int rt_get_scheduling_error(void)

When the EDF scheduling policy is used, returns the ``scheduling error'' $\epsilon_{i,j} = d_{i,j} - r_{i,j}$ for a periodic task. The scheduling error is defined as the difference between the absolute deadline of the reserve serving a task and the task activation time.

In general, if $\epsilon > 0$ the task is not reserved enough time per period.