epics-base/documentation/new-notes/PR-744.md

Avoid early expiration of timers on non-RTOS IOCs

Previously the epicsTimer code rounded down user requested delays by subtracting one half of the sleep "quantum". On RTEMS and vxWorks, this allowed periodic timers which expired on every tick. However this also resulted in timers expiring slightly earlier than requested.

With PR 744 rounding is only done for RTEMS and vxWorks, which still have tick timers.

This affects several facilities which use epicsTimer, including record delays. For example, calcout.ODLY becomes more accurate on non-RTOS IOCs.