1 Rutgers UniversityCS 416: Operating Systems Final exam details December 22, pm-3pm. Venue: SEC 118. Tips: Spend time reading the questions before answering them. Prioritize the questions and answer questions in an order that will ensure that you maximize your score

2 Rutgers UniversityCS 416: Operating Systems I/O Blocking, non-blocking, and asynchronous I/O. Differences? Pros and cons? Buffered and unbuffered I/O. Differences? Pros and cons? Programmed I/O and DMA. Differences? Pros and cons? Steps in performing a DMA operation? Steps in performing an I/O operation?

3 Rutgers UniversityCS 416: Operating Systems Disks and Disk Management Structure. Sectors, tracks, cylinders? Performance. Seek latency, rotational latency, transfer rate? Disk scheduling. FCFS, SSTF, SCAN, C-SCAN, LOOK, C- LOOK? Pros and cons? RAID. Different RAID levels? Pros and cons?

4 Rutgers UniversityCS 416: Operating Systems File Systems File allocation. Contiguous, linked, indexed? Pros and cons? Free space management. Bit map, chained, indexed? Pros and cons? Buffer cache. How does it work? Consistency? Replacements? File sharing semantics. Unix, session, immutable files? Protection. Protection domains? Access control lists, capabilities? Pros and cons?

5 Rutgers UniversityCS 416: Operating Systems Security Buffer overflow vulnerabilities. Stack smashing attacks. Tricks to make stack smashing attacks work in practice (see Aleph One paper and slides). Techniques to prevent buffer overflow attacks.

6 Rutgers UniversityCS 416: Operating Systems Distributed Systems Fault models. Failstop, crash, Byzantine? Consensus and coordinated attack results. Why are they impossible? Communication protocols. Layering? Function of application, transport, network, and link/physical layers? Examples? Internet protocols. IP, UDP, TCP? TCP flow control? TCP congestion control? RPC. Goal? Stubs? Deviations from regular PC? Semantics? Transactions. ACID? Two-phase locking and commit? Distributed algorithms. Happened before? Mutual exclusion algorithms? Properties? Material on distributed file systems will NOT be on the final.

7 Rutgers UniversityCS 416: Operating Systems Architecture Caching. Why? Examples? When does it work well? Invoking the OS. Mechanisms? Differences? I/O event notification. Mechanisms? Differences? Send/receive data to I/O devices. Mechanisms? Differences?

8 Rutgers UniversityCS 416: Operating Systems Processes and Threads Stack. Activation records. What is stored there? Heap. What is stored there? Address space. What is it? Process context. Thread context. What do they comprise? PCB. TCB. Where are they stored? What do they store? Context switching. How does it happen? Any problems? Thread states. User-level and kernel-level threads. Pros and cons?

9 Rutgers UniversityCS 416: Operating Systems Synchronization Critical section. Locks. Semaphores. Monitors. Atomic operations. Examples? Spinning vs. blocking. Tradeoff? Deadlock. Necessary conditions? Techniques for tackling deadlocks? Banker’s algorithm.

10 Rutgers UniversityCS 416: Operating Systems CPU Scheduling Metrics: thruput, utilization, turnaround, response time, deadlines Preemption. Policies: FCFS, SJF, RR, Priorities, Feedback. Pros and cons.

11 Rutgers UniversityCS 416: Operating Systems Memory Management Paging. Segmentation. How do they work? Pros and cons? Translation Lookaside Buffer. How does it work? How are misses handled? Translation from logical (virtual) to physical address. How? Page tables. Where are they stored? What can we do to reduce their size? Page replacement policies: FIFO, LRU, Optimal, 2 nd chance, Nth chance. Working set. Thrashing. Swapping.

12 Rutgers UniversityCS 416: Operating Systems File systems File system implementation. Layout and management of disk pages. Inodes and directory entries. UNIX-like inodes. Managing free space. Bitmaps and free lists. File system consistency semantics. Log-structured file system implementation. Tradeoffs and design criteria. Segment cleaning mechanisms and policies. Tradeoffs.