This read-write value sets the percentage of refill cycles that use the priority order 1, 2, 3, 0, meaning cycles where priority-1 traffic gets served first instead of priority-0. An admin uses this, together with the Priority0, Priority2, and Priority3 siblings, to fine-tune how much relative preference priority-1 traffic gets versus the port's top class, useful when priority-1 carries something important but not as critical as priority-0. For example, raising lportXmitRefillPriority1Percentage while lowering Priority0Percentage shifts more scheduling cycles toward favoring priority-1 traffic over the absolute top class.