CGS 3763 Operating Systems Concepts Spring 2013 Dan C. Marinescu Office: HEC 304 Office hours: M-Wd 11:30 - 12:30 AM

Lecture 30 – Friday, March 29, 2013 Last time: Today Next time Atomicity Coordination with a bounded buffer Today Student questions Review for the midterm Next time Midterm Reading assignments Chapters 6, 7, 8 of the textbook em=LOCKED Lecture 30

From Wednesday March 20th lecture. Thread coordination, can cause deadlocks and priority inversion. Is there another method like the various CPU scheduling processes in which we can avoid deadlocking? Clarify how a deadlock occurs and its outcomes. What is the most common mechanism for avoiding deadlocks? Will a deadlock completely stop a program? Will the program simply stop running and crash the system? If two processes have end up in a race condition, how does the system decide which to allow running first? What exactly does busy-waiting mean? Can a process be busy-waiting on a single core single processor system? Further explanation of Isolation in regards to the ACID principles. If ACID is followed, does that guarantee that the transaction will complete/fail as a unit or are there other factors involved in this? When comparing two OS’s, is the one with more ACID better? What does atomicity mean? What is the importance of serialization? Lecture 30

From Friday March 22th lecture In the concept of contention scope, how do the threads compete? How does the thread library in PCS schedule the threads that compete? What if you have multiple kernel threads? Thread deadlocks, I know that thread deadlocks occur when two threads are holding resources that the other requires, but I don’t understand how to fix the problem. Can you explain priority inversion again? How often do deadlocks occur? Lecture 30