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  2. Page replacement algorithm - Wikipedia

    en.wikipedia.org/wiki/Page_replacement_algorithm

    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 ...

  3. Cache replacement policies - Wikipedia

    en.wikipedia.org/wiki/Cache_replacement_policies

    Bélády's algorithm is the optimal cache replacement policy, but it requires knowledge of the future to evict lines that will be reused farthest in the future. A number of replacement policies have been proposed which attempt to predict future reuse distances from past access patterns, [23] allowing them to approximate the optimal replacement ...

  4. Working set - Wikipedia

    en.wikipedia.org/wiki/Working_set

    The main hurdle in implementing the working set model is keeping track of the working set. The working set window is a moving window. At each memory reference a new reference appears at one end and the oldest reference drops off the other end. A page is in the working set if it is referenced in the working set window.

  5. LIRS caching algorithm - Wikipedia

    en.wikipedia.org/wiki/LIRS_caching_algorithm

    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.

  6. Bélády's anomaly - Wikipedia

    en.wikipedia.org/wiki/Bélády's_anomaly

    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]

  7. Memory paging - Wikipedia

    en.wikipedia.org/wiki/Memory_paging

    When all page frames are in use, the operating system must select a page frame to reuse for the page the program now needs. If the evicted page frame was dynamically allocated by a program to hold data, or if a program modified it since it was read into RAM (in other words, if it has become "dirty"), it must be written out to disk before being ...

  8. Least frequently used - Wikipedia

    en.wikipedia.org/wiki/Least_frequently_used

    Least Frequently Used (LFU) is a type of cache algorithm used to manage memory within a computer. The standard characteristics of this method involve the system keeping track of the number of times a block is referenced in memory.

  9. Reservoir sampling - Wikipedia

    en.wikipedia.org/wiki/Reservoir_sampling

    Reservoir sampling is a family of randomized algorithms for choosing a simple random sample, without replacement, of k items from a population of unknown size n in a single pass over the items.