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CS 162 Discussion Section Week 5

This discussion focuses on important aspects of operating systems, covering the project submission deadline and how autograding works. We delve into the role of OS schedulers in managing CPU utilization and evaluating performance metrics like throughput, waiting time, and response time. Additionally, we summarize the need for memory management, including isolation, programming ease, and dynamic library support. The session also addresses memory segmentation, fragmentation issues, and page table sizes in 64-bit systems, providing insights into address translation methods.

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CS 162 Discussion Section Week 5

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Presentation Transcript

  1. CS 162Discussion SectionWeek 5

  2. Administrivia • Project code submission due Tuesday midnight • Autograder is up and running • Boat problem

  3. What does an OS scheduler do?

  4. Image Source: macdesign.net

  5. How would you measure the effectiveness of a scheduler? • CPU Utilization • Throughput • Waiting time • Service time • Turnaround time for a process • Response time

  6. Work sheet time

  7. Recap: Why do we need memory management in the OS? • Isolation / Protection • Ease of programming • Re-locatable code • Support for Dynamic Libraries • Support larger address spaces (Program independent of hw availability)

  8. Memory Hierarchy Image Source: http://www.sal.ksu.edu/faculty/tim/ossg/

  9. What are the typical segments in a process’ address space? • Code • Data • Stack • Heap

  10. Seg Offset 15 14 13 0 0x0000 0x0000 0x4000 0x4000 0x4800 0x5C00 0x8000 0xC000 0xF000 Virtual Address Space Physical Address Space Virtual Address Format SegID = 0 Might be shared SegID = 1 Space for Other Apps Shared with Other Apps

  11. What is the problem with Memory Segmentation? • Fragmentation! • Inter-process sharing is hard What is the solution?

  12. What is the size of the page table in a 64bit system if each page is 4K in size?

  13. What is the problem with large pages?What is the solution to large page tables?

  14. How does address translation really take place?

  15. What is the size of the page table in a 64bit system if each page is 4K in size? – 16 PBHow many levels would you need if you had 1024 entry page tables?

  16. Linear inverted page tables

  17. Hashed inverted page table

  18. Hashed inverted page table

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