From your past experience you should already be familiar with the following concepts (you can brush up by consulting your favorite operating systems textbook.
Synchronization: critical section , monitors, semaphores
Deadlock prevention and detection algorithms
Scheduling, FIFO, LIFO, priority queue, SJF, ready queue
Memory management: virtual memory, segmented memory, caches
File management
Protection mechanisms: kernel vs user modes, memory protection
Concept of virtual machines: processes, resources