Editing Page fault (section)

== Performance impact ==

Page faults degrade system performance and can cause [[thrashing (computer science)|thrashing]]. Major page faults on a conventional computer using [[hard disk drive]]s can have a significant impact on their performance, as a typical hard disk drive had an average [[rotational latency]] of 3&nbsp;ms, a [[seek time]] of 5&nbsp;ms and a transfer time of 0.05&nbsp;ms/page. Therefore, the total time for paging is near 8&nbsp;ms (8,000&nbsp;μs). If the memory access time is 0.2&nbsp;μs, then the page fault would make the operation about 40,000 times slower. With a more modern system using a fast [[solid-state drive]] with a page read latency of 0.030&nbsp;ms (30&nbsp;μs)<ref>{{Cite web |last=W1zzard |last2= |date=2023-08-08 |title=Samsung 990 Pro 2 TB Review |url=https://www.techpowerup.com/review/samsung-990-pro-2-tb/5.html |access-date=2025-05-19 |website=TechPowerUp |language=en |publication-date=}}</ref> and a memory access latency of 70&nbsp;ns (0.070&nbsp;μs),<ref>{{Cite web |last=W1zzard |last2= |last3= |first3= |date=2024-08-07 |title=AMD Ryzen 5 9600X Review - The Best Sub-$300 Gaming CPU |url=https://www.techpowerup.com/review/amd-ryzen-5-9600x/6.html |access-date=2025-05-19 |website=TechPowerUp |language=en}}</ref> a hard page fault is still over 400 times slower.

Performance [[Optimization (computer science)|optimization]] of programs or operating systems often involves efforts to reduce the number of page faults. Two primary focuses of the optimization are reducing overall memory usage and improving [[memory locality]]. To reduce the page faults, OS developers must use an appropriate [[page replacement algorithm]] that maximizes the page hits. Many have been proposed, such as implementing [[heuristic algorithm]]s to reduce the incidence of page faults.

Larger physical memory also reduces the likelihood of page faults. Chunks of [[Memory-mapped file|memory-mapped files]] can remain in memory longer and avoid slow re-reads from storage. Similarly, lower memory pressure lessens the need for frequent [[Memory paging|swapping out]] of memory pages to a backing storage device used for swap.