1. CPSC 457 Operating Systems
Lecture 8
Memory Management: Virtual Memory

2. Last Time Memory Management Midterm Review Address Space
Base and Limit Registers
How do we store processes
Swapping
Free Memory Management
Midterm Review
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3. This Time Midterm Virtual Memory Fragmentation Paging Page Tables
Translation Look-aside Buffers
Page Faults
Locality
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4. Memory Fragmentation
External
Internal
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5. Virtual Memory
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6. Paging Frame Page Page Table Fixed-Sized block of Physical Memory
Fixed-Sized block of Logical Memory
Page Table
Maps the Pages on to the Frames
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7. Page Address
Page Number
Page Offset
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8. Paging can be EXPENSIVE
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9. Translation Look-aside Buffer
Associative High Speed Memory
high speed lookup cache
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10. Big Page Tables Hierarchical Page Tables Hashed / Clustered Paging
Lookups for the page table
Hashed / Clustered Paging
Hash Table entries, possibly gather related pages
Inverted Page Table
Track all frames and which pages are assigned to them
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11. Virtual Memory
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12. How to Implement Virtual Memory
Demand Paging
Load pages into memory only when you need them
Page Fault
When you access memory and discover no page
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13. Next Time Memory Management Page Replacement Algorithms Concurrency
How to manage the problems when processes run at the same time
Classical problems of Computer Science
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