CSE 120 Principles of Operating Systems Fall 2001 Final Review Geoffrey M Voelker Course Plugs If you like CSE 120 topics you might find some other courses interesting CSE 121 OS Arch and Implementation Sp Yee CSE 123A B Computer Networking Sp Sp OS Implementation using BSD 4 4 as a case study Projects modify BSD 4 4 kernel 123A Varghese link layer up to internetworking IP 123B Savage internetworking up to session application CSE 128 Concurrency Sp Marzullo Whole quarter of concurrency Much more in depth treatment extends to distributed domain November 28 2001 CSE 120 Final Review 2 1 Course Plugs 2 CSE 190 Software System Design and Implementation Voelker One project the entire quarter Distributed real time multiplayer 3D game It might not seem like it but it is not really a games course Groups of six Three lectures then weekly group meetings Basically you do all the work No homeworks exams Oriented towards graduating seniors By instructor permission only November 28 2001 CSE 120 Final Review 3 Overview Final mechanics Memory management Paging Page replacement Disk I O File systems Advanced topics November 28 2001 CSE 120 Final Review 4 2 Final Mechanics Bulk of the final covers material after midterm Some material on concurrency synchronization I will use at least one question from this review on the exam Closed book one 8 5 x11 sheet of notes Synch primitives synch problems Based upon lecture material homeworks and project Memory management file systems advanced topics Just one Sample final on class web site Again please do not cheat Cheating has been a minimum would like to keep it that way November 28 2001 CSE 120 Final Review 5 Memory Management Why is memory management useful 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 Why do we have virtual memory if it is so complex Page replacement What are the overheads related to providing memory management November 28 2001 CSE 120 Final Review 6 3 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 November 28 2001 CSE 120 Final Review 7 Paging How is paging different from partitioning What are the advantages disadvantages of paging What are page tables What are page table entries PTE Know these terms Virtual page number VPN page frame number PFN offset Know how to break down virtual addresses into page numbers offset How have you implemented paging in Nachos November 28 2001 CSE 120 Final Review 8 4 Page Table Entries What is a page table entry In Nachos What are all of the PTE bits used for Modify Reference Valid Protection November 28 2001 CSE 120 Final Review 9 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 November 28 2001 CSE 120 Final Review 10 5 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 November 28 2001 CSE 120 Final Review 11 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 November 28 2001 CSE 120 Final Review 12 6 Page Faults What is a page fault How is it used to implement demand paged virtual memory What is the complete sequence of steps from a TLB miss to paging in from disk for translating a virtual address to a physical address What is done in hardware what is done in software November 28 2001 CSE 120 Final Review 13 Advanced Mem Management What is shared memory What is copy on write What are memory mapped files November 28 2001 CSE 120 Final Review 14 7 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 Understand Belady s optimal FIFO LRU Approximate LRU LRU Clock Working Set Page Fault Frequency What is thrashing November 28 2001 CSE 120 Final Review 15 Disk Understand the memory hierarchy concept locality Physical disk structure Disk interface Platters surfaces tracks sectors cylinders arms heads How does the OS make requests to the disk Disk performance What steps determine disk request performance What are seek rotation transfer November 28 2001 CSE 120 Final Review 16 8 Disk Scheduling How can disk scheduling improve performance What are the issues in disk scheduling Response time throughput fairness Understand FCFS SSTF SCAN C SCAN November 28 2001 CSE 120 Final Review 17 File Systems Topics Files Directories Sharing Protection Layouts Buffer Cache What is a file system Why are file systems useful why do we have them November 28 2001 CSE 120 Final Review 18 9 Files and Directories What is a file What is a directory What operations are supported What characteristics do they have What are file access methods What are they used for How are the implemented What is a directory entry How are directories used to do path name translation November 28 2001 CSE 120 Final Review 19 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 November 28 2001 CSE 120 Final Review 20 10 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 November 28 2001 CSE 120 Final Review 21 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 November 28 2001 CSE 120 Final Review 22 11 Advanced Topics What is FFS and how is it an improvement over the original Unix file system What is LFS and how is it an improvement over FFS What is RAID and how does it help
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