Page Fault - Performance

Performance

Page faults, by their very nature, degrade the performance of a program or operating system and in the degenerate case can cause thrashing. Optimizations to programs and the operating system that reduce the number of page faults improve the performance of the program or even the entire system. The two primary focuses of the optimization effort are reducing overall memory usage and improving memory locality. Generally, making more physical memory available also reduces page faults. Many page replacement algorithms have been proposed, such as implementing heuristic-based algorithms to reduce the incidence of page faults.

An average hard disk has an average rotational latency of 3ms, a seek-time of 5ms, and a transfer-time of 0.05ms/page. So the total time for paging comes in near 8ms (8 000 000 ns). If the memory access time is 200ns, then the page fault would make the operation about 40,000 times slower. To reduce the page faults in the system, programmers must make use of an appropriate page replacement algorithm that suits the current requirements and maximizes the page hits.

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