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Class Discussion. Questions. What are the key ideas that improve performance in the Synthesis approach? Which underlying problems do they address? How does it address lock contention? How does it address locality?
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Class Discussion CS533 - Concepts of Operating Systems
Questions • What are the key ideas that improve performance in the Synthesis approach? • Which underlying problems do they address? • How does it address lock contention? • How does it address locality? • Is extensive use of optimistic concurrency control via CAS immune to memory/bus contention problems? • Are there other kinds of contention to worry about? CS533 - Concepts of Operating Systems
Questions • Why do synchronized clocks cause contention if the run queue is protected by a single lock? • How can you “localize” thread switching? • 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” ? • Why might you chose to leave a deleted element in place? CS533 - Concepts of Operating Systems
Questions • Are the lock-free solutions presented in the paper wait-free? • 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) • How can you overcome these in an optimistic approach? CS533 - Concepts of Operating Systems