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EXAM 2 COP4610 FSU WANG UPDATED
EXAM WITH VERIFIED SOLUTIONS.
Demand paging - correct answer -Allows pages that are
referenced actively to be loaded into memory
Page fault - correct answer -Not present
Transparent page fault - correct answer -(invisible) mechanisms
A process does not know how it happened
Belady's anomaly - correct answer -Getting more page faults by
increasing the memory size
Thrashing - correct answer -Occurs when the memory is
overcommitted
Working set - correct answer -A set of pages that was referenced
in the previous T seconds
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Steps to carry out a page fault - correct answer -1. Choose a
page
2. If the page has been modified, write its contents to disk
3. Change the corresponding page table entry and TLB entry
4. Load new page into memory from disk
5. Update page table entry
6. Continue the thread
Page replacement policies - correct answer -Random
replacement: replace a random page
+ Easy to implement in hardware (e.g., TLB)
- May toss out useful pages
First in, first out (FIFO): toss out the oldest page
+ Fair for all pages
- May toss out pages that are heavily used
Optimal (MIN): replaces the page that will not be used for the
longest time
+ Optimal
- Does not know the future
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Least-recently used (LRU): replaces the page that has not been
used for the longest time
+ Good if past use predicts future use
- Tricky to implement efficiently
Least frequently used (LFU): replaces the page that is used least
often
Tracks usage count of pages
+ Good if past use predicts future use
- Difficult to replace pages with high counts
Polling: - correct answer -a CPU repeatedly checks the status of a
device for exchanging data
Interrupt-driven I/Os - correct answer -A device controller notifies
the corresponding device driver when the device is available
Direct memory access (DMA) - correct answer -Uses an
additional controller to perform data movements
EXAM 2 COP4610 FSU WANG UPDATED
EXAM WITH VERIFIED SOLUTIONS.
Demand paging - correct answer -Allows pages that are
referenced actively to be loaded into memory
Page fault - correct answer -Not present
Transparent page fault - correct answer -(invisible) mechanisms
A process does not know how it happened
Belady's anomaly - correct answer -Getting more page faults by
increasing the memory size
Thrashing - correct answer -Occurs when the memory is
overcommitted
Working set - correct answer -A set of pages that was referenced
in the previous T seconds
, Page | 2
Steps to carry out a page fault - correct answer -1. Choose a
page
2. If the page has been modified, write its contents to disk
3. Change the corresponding page table entry and TLB entry
4. Load new page into memory from disk
5. Update page table entry
6. Continue the thread
Page replacement policies - correct answer -Random
replacement: replace a random page
+ Easy to implement in hardware (e.g., TLB)
- May toss out useful pages
First in, first out (FIFO): toss out the oldest page
+ Fair for all pages
- May toss out pages that are heavily used
Optimal (MIN): replaces the page that will not be used for the
longest time
+ Optimal
- Does not know the future
, Page | 3
Least-recently used (LRU): replaces the page that has not been
used for the longest time
+ Good if past use predicts future use
- Tricky to implement efficiently
Least frequently used (LFU): replaces the page that is used least
often
Tracks usage count of pages
+ Good if past use predicts future use
- Difficult to replace pages with high counts
Polling: - correct answer -a CPU repeatedly checks the status of a
device for exchanging data
Interrupt-driven I/Os - correct answer -A device controller notifies
the corresponding device driver when the device is available
Direct memory access (DMA) - correct answer -Uses an
additional controller to perform data movements
