In particular, since we spent so much time on pthreads (with the associated mutexes and condition variables) in class, you can expect at least one question on this. We spent a lot of time on operating system structures and system calls, so expect at least one question on this. Two complete lectures were spent on CPU Scheduling algorithms, and three lectures covered mutual exclusion algorithms and semaphores, so it seems reasonable that there will be questions on these things. We studied processes and operations on processes, so expect something on that. We covered in detail Interprocess Communications (IPC), so expect a question on that.
In general, if you have attended class regularly, read the textbook, and understood our in-class discussions, you can expect to do reasonably well.