Paging Flashcards
Definition of FIFO
(First come first serve)
Simplest page replacement algorithm. The frame that has been in the memory the longest is replaced
Pro’s/Con’s of FIFO
- has the most number of page fault
- suffers from Beladys anomely
- used in OS
- simplest to implement
Define LRU
The page that is replaced is the least recently used
Pro’s/Con’s of LRU
- doesn’t suffer from beladys anomely
- used in OS
- okay to implement
- more page faults than OPT and less page faults than FIFO
Define OPT paging
The page who’s next use is furthest in the future is swapped out
Pro’s / Con’s of OPT
- least number of page faults
- doesn’t suffer from beladys anomely
- not used in OS
- Difficult to implement
What is paging and swapping?
Where is it placed?
Management strategies
In the main memory for execution
Pro’s / Con’s of Demand Paging
Virtual memory management method, the o/s copies a disk page to the physical memory if there has been attempts to access the page or if it’s not in the memory
+ allows many processes to run in OS
- les flexible as it moves entire process back and forth from main memory to back store
- allows less processed to stay in memory
Pro’s / Con’s of Swapping Paging
Copying the entire process address space to the swap device
+ allows memory address space of process to be non-contagious
+ more flexible as only pages of a process are moved
+ allows more processes to stay in memory
Paging
Why is it used
Memory management method where a computer stores and retrieves data from the secondary storage to use in the main memory
Ram sizes are not increasing but the number and complexity of programs and applications are which take up a lot of space in the RAM so paging is used to help manage this
What causes a page fault
When a program request data that isn’t in the real memory causing the o/s to retrieve the data from the virtual memory and load it into the ram
