6 3ULQFLSOHV RI 2SHUDWLQJ 6 VWHPV DOO Final Review Geoffrey M Voelker 2YHUYLHZ Final mechanics Memory management Paging Page replacement Disk I O File systems Advanced topics December 5 2000 CSE 120 Final Review 2 1 LQDO 0HFKDQLFV Bulk of the final covers material after midterm Some material on threads synchronization Memory management file systems advanced topics Thread operations semaphores Based upon lecture material homeworks and project I will use at least one question from this review on the exam Closed book one 8 5 x11 sheet of notes Again please do not cheat Cheating has been a minimum would like to keep it that way December 5 2000 CSE 120 Final Review 3 0HPRU 0DQDJHPHQW 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 December 5 2000 CSE 120 Final Review 4 2 9LUWXDOL LQJ 0HPRU 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 December 5 2000 CSE 120 Final Review 5 3DJLQJ 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 December 5 2000 CSE 120 Final Review 6 3 3DJH 7DEOH QWULHV What is a page table entry In Nachos What are all of the PTE bits used for Modify Reference Valid Protection December 5 2000 CSE 120 Final Review 7 6HJPHQWDWLRQ 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 December 5 2000 CSE 120 Final Review 8 4 3DJH 7DEOHV 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 page tables work December 5 2000 CSE 120 Final Review 9 7 V What problem does the TLB solve How do TLBs work Why do TLBs work How are TLBs managed What happens on a TLB miss fault What is the difference between a hardware and software managed TLB December 5 2000 CSE 120 Final Review 10 5 3DJH DXOWV 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 December 5 2000 CSE 120 Final Review 11 GYDQFHG 0HP 0DQDJHPHQW What is shared memory What is copy on write What are memory mapped files December 5 2000 CSE 120 Final Review 12 6 3DJH 5HSODFHPHQW 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 December 5 2000 CSE 120 Final Review 13 LVN 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 December 5 2000 CSE 120 Final Review 14 7 LVN 6FKHGXOLQJ How can disk scheduling improve performance What are the issues in disk scheduling Response time throughput fairness Understand FCFS SSTF SCAN C SCAN December 5 2000 CSE 120 Final Review 15 LOH 6 VWHPV Topics Files Directories Sharing Protection Layouts Buffer Cache What is a file system Why are file systems useful why do we have them December 5 2000 CSE 120 Final Review 16 8 LOHV DQG LUHFWRULHV 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 December 5 2000 CSE 120 Final Review 17 3URWHFWLRQ 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 December 5 2000 CSE 120 Final Review 18 9 LOH 6 VWHP D RXWV 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 December 5 2000 CSE 120 Final Review 19 LOH XIIHU DFKH 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 December 5 2000 CSE 120 Final Review 20 10 GYDQFHG 7RSLFV 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 file system performance and reliability What is RPC and how is it implemented December 5 2000 CSE 120 Final Review 21 RQFOXVLRQ See you Thursday morning bright and early CSB 001 8am Good luck December 5 2000 CSE 120 Final Review 22 11
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