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1 definition found
 for demand paging
From The Free On-line Dictionary of Computing (30 December 2018) :

  demand paging
  demand paged
  
      A kind of virtual memory where a page
     of memory will be paged in if an attempt is made to access
     it and it is not already present in main memory.  This
     normally involves a memory management unit which looks up
     the virtual address in a page map to see if it is paged
     in.  If it is not then the operating system will page it in,
     update the page map and restart the failed access.  This
     implies that the processor must be able to recover from and
     restart a failed memory access or must be suspended while some
     other mechanism is used to perform the paging.
  
     Paging in a page may first require some other page to be moved
     from main memory to disk ("paged out") to make room.  If this
     page has not been modified since it was paged in, it can
     simply be reused without writing it back to disk.  This is
     determined from the "modified" or "dirty" flag bit in the
     page map.  A replacement algorithm or policy is used to
     select the page to be paged out, often this is the least
     recently used (LRU) algorithm.
  
     Prepaging is generally more efficient than demand paging.
  
     (1998-04-24)
  

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