Search results
Results From The WOW.Com Content Network
The theoretically optimal page replacement algorithm (also known as OPT, clairvoyant replacement algorithm, or Bélády's optimal page replacement policy) [3] [4] [2] is an algorithm that works as follows: when a page needs to be swapped in, the operating system swaps out the page whose next use will occur farthest in the future. For example, a ...
LIRS is a page replacement algorithm with better performance than LRU and other, newer replacement algorithms. Reuse distance is a metric for dynamically ranking accessed pages to make a replacement decision. [32] LIRS addresses the limits of LRU by using recency to evaluate inter-reference recency (IRR) to make a replacement decision.
For example, Graph (c) is produced after page E is accessed on Graph (a). When there is a miss and a resident page has to be replaced, the resident HIR page at the bottom of Stack Q is selected as the victim for replacement. For example, Graphs (d) and (e) are produced after pages D and C are accessed on Graph (a), respectively.
This phenomenon is commonly experienced when using the first-in first-out page replacement algorithm. In FIFO, the page fault may or may not increase as the page frames increase, but in optimal and stack-based algorithms like LRU, as the page frames increase, the page fault decreases. László Bélády demonstrated this in 1969. [1]
The method the operating system uses to select the page frame to reuse, which is its page replacement algorithm, is important to efficiency. The operating system predicts the page frame least likely to be needed soon, often through the least recently used (LRU) algorithm or an algorithm based on the program's working set. To further increase ...
Adaptive Replacement Cache (ARC) is a page replacement algorithm with better performance [1] than LRU (least recently used). This is accomplished by keeping track of both frequently used and recently used pages plus a recent eviction history for both. The algorithm was developed [2] at the IBM Almaden Research Center.
A page table entry or other per-page information may also include information about whether the page has been written to (the dirty bit), when it was last used (the accessed bit, for a least recently used (LRU) page replacement algorithm), what kind of processes (user mode or supervisor mode) may read and write it, and whether it should be ...
Which page to page out is the subject of page replacement algorithms. Some MMUs trigger a page fault for other reasons, whether or not the page is currently resident in physical memory and mapped into the virtual address space of a process: Attempting to write when the page table has the read-only bit set causes a page fault.