So if T1(priority 3, arrived first) was preempted it is put back to the runqueue. If there is already T4(priority 3, arrived fourth) inside the runqueue, which one of these two will be handled first?! FCFS algorithm should decide, however T1 arrived to the runque first, than it left runque, when it was absent T4 arrived and T1 returned to runqueue. So should this FCFS select T1 over T4, or T4 over T1?
I think it should select T4 because it technically will be ahead of T1 in runqueue, unless however runqueu will compare them based on their first appearance in the runqueue in which case T1 will be selected. P.S. I am driving nuts with this. Help