- When we schedule the next collection for a service, we should add the interval to the current time, but we should subtract the difference of the current time (after the service was collected this round) and the start of collection this round.  This way, the interval is always the configured value, rather than the configured value plus the collection delay.
- When we record the collection results to the RRD, we should use the time of the start of the collection, rather than the current time after collection completes.  That way, the time value for a given OID of a given service is always at the configured interval.