CS533 - Concepts of Operating Systems 1 Class Discussion

CS533 - Concepts of Operating Systems 2 Questions  What are the key ideas that improve performance in the Synthesis approach? o Which underlying problems do they address? o How does it address lock contention? o How does it address locality?  Is extensive use of optimistic concurrency control via CAS immune to memory/bus contention problems? o Are there other kinds of contention to worry about?

CS533 - Concepts of Operating Systems 3 Questions  Why do synchronized clocks cause contention if the run queue is protected by a single lock?  How can you “localize” thread switching? o How far can you push this idea in other areas of the OS?  What general approaches can you take to reduce “interference”?  What does it mean for a deleted list element to be “safe” ? o Why might you chose to leave a deleted element in place?

CS533 - Concepts of Operating Systems 4 Questions  Are the lock-free solutions presented in the paper wait-free? o If not, why not?  What problems does the naïve approach to lock-free synchronization suffer from (i.e., copy data structure and flip pointer to it) o How can you overcome these in an optimistic approach?