CSE 120: Operating Systems - Final Review and Course Recommendations - Prof. Geoffrey M. V, Study notes of Computer Science

Download CSE 120: Operating Systems - Final Review and Course Recommendations - Prof. Geoffrey M. V and more Study notes Computer Science in PDF only on Docsity! Lecture 17: Final Review CSE 120: Principles of Operating Systems Alex C. Snoeren Project 3 due 12/4 CSE 120 – Lecture 172 Course Plugs  If you liked CSE 120 topics, you might find some other courses interesting  CSE 121: OS Architecture and Implementation ◆ Wi06 (Your’s truly) ◆ OS Implementation using Unix as a case study ◆ System projects with experimentation  CSE 123A/B: Computer Networking ◆ 123A, Fa06 (Varghese) – link layer up to internetworking (IP) ◆ 123B, Sp06 (Vahdat) – internetworking up to application CSE 120 – Lecture 175 Final Mechanics  Bulk of the final covers material after midterm ◆ Memory management, file systems, security  Some material on concurrency, synchronization ◆ Synch primitives, synch problems  Based upon lecture material, homeworks, and project ◆ Likely to be questions on Nachos  Closed book, no notes ◆ Expect similar style to midterm, just longer  Again, please, do not cheat. ◆ I want you all to graduate CSE 120 – Lecture 176 Memory Management  Why is memory management useful? ◆ Why do we have virtual memory if it is so complex?  What are the mechanisms for implementing MM? ◆ Physical and virtual addressing ◆ Partitioning, paging, and segmentation ◆ Page tables, TLB  What are the policies related to MM? ◆ Page replacement  What are the overheads related to providing memory management? CSE 120 – Lecture 177 Virtualizing Memory  What is the difference between a physical and virtual address?  What is the difference between fixed and variable partitioning? ◆ How do base and limit registers work?  What is internal fragmentation?  What is external fragmentation?  What is a protection fault? CSE 120 – Lecture 1710 Segmentation  What is segmentation?  How does it compare/contrast with paging?  What are its advantages/disadvantages with respect to partitioning, paging?  What is a segment table?  How can paging and segmentation be combined? CSE 120 – Lecture 1711 Page Tables  Page tables introduce overhead ◆ Space for storing them ◆ Time to use them for translation  What techniques can be used to reduce their overhead?  How do two-level (multi-level) page tables work? CSE 120 – Lecture 1712 TLBs  What problem does the TLB solve?  How do TLBs work?  Why are TLBs effective?  How are TLBs managed? ◆ What happens on a TLB miss fault?  What is the difference between a hardware and software managed TLB? CSE 120 – Lecture 1715 Page Replacement  What is the purpose of the page replacement algorithm?  What application behavior does page replacement try to exploit?  When is the page replacement algorithm used?  Different replacement algorithms ◆ Belady’s (optimal), FIFO, LRU, Approximate LRU, LRU Clock, Working Set, Page Fault Frequency  What is Belady’s anomaly? thrashing? CSE 120 – Lecture 1716 Disk  Understand the memory hierarchy concept, locality  Physical disk structure ◆ Platters, surfaces, tracks, sectors, cylinders, arms, heads  Disk interface ◆ How does the OS make requests to the disk?  Disk performance ◆ What steps determine disk request performance? ◆ What are seek, rotation, transfer? CSE 120 – Lecture 1717 Disk Scheduling  How can disk scheduling improve performance?  What are the issues in disk scheduling? ◆ Response time, throughput, fairness  Review ◆ FCFS, SSTF, SCAN, C-SCAN ◆ Know why or why not these might still be important CSE 120 – Lecture 1720 Protection  What is file protection used for?  How is it implemented?  What are access control lists (ACLs)?  What are capabilities?  What are the advantages/disadvantages of each? CSE 120 – Lecture 1721 File System Layouts  What are file system layouts used for?  What are the general strategies? ◆ Contiguous, linked, indexed?  What are the tradeoffs for those strategies?  How do those strategies reflect file access methods?  What is an inode? ◆ How are inodes different from directories? ◆ How are inodes and directories used to do path resolution, find files? CSE 120 – Lecture 1722 File Buffer Cache  What is the file buffer cache, and why do operating systems use one?  What is the difference between caching reads and caching writes?  What are the tradeoffs of using memory for a file buffer cache vs. VM? CSE 120 – Lecture 1725 Security  Trusted Computing Base (TCB)  Basics of cryptography ◆ Difference between authenticity, confidentiality, integrity? ◆ What is meant by encryption and signing? ◆ Why is authentication not authorization, and v.v.?  Best current practices ◆ Principle of least privilege ◆ Principle of least common mechanism ◆ Complete mediation (ToCTToU) ◆ Covert channels, (in-) security through obscurity CSE 120 – Lecture 1726 The End!  Congratulations on surviving CSE 120 ◆ It’s a challenging course, but I hope you found it worthwhile  Project 3 extension ◆ Due Sunday night at Midnight ◆ But don’t neglect studying (for this class and others)  See you Tuesday 12/6 ◆ CENTR 109 @ 11:30am-2:30pm  Good luck, and thanks for a great class!