memory management - What is the difference between demand paging and page replacement? -


from understand, demand paging paging swapping, can swap in page when needed. page replacement seems more or less same thing, bring in page needed , switching existing page in physical memory.

so there distinct difference?

in system uses demand paging, operating system copies disk page physical memory if attempt made access , page not in memory (i.e., if page fault occurs). follows process begins execution none of pages in physical memory, , many page faults occur until of process's working set of pages located in physical memory. example of lazy loading technique.

demand paging follows pages should brought memory if executing process demands them. referred lazy evaluation only pages demanded process swapped secondary storage main memory. contrast pure swapping, memory process swapped secondary storage main memory during process startup.

whereas, page replacement technique done when there occurs page-fault. page replacement technique utilised both pure swapping , demand-paging.


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