What is Demand Paging?

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Definition

• Demand paging is a process which involves the copying and relocation of data from a secondary storage system to random access memory (RAM), a main memory storage system. Demand paging copies and relocates data to facilitate the fastest access to that data. Once the data is relocated, demand paging sends a command to the operating system to inform it that the data file or files are now ready to be loaded. Demand paging is performed on demand, or after a command has been sent to retrieve specific data.

Advantages

• Advantages of demand paging includes less loading time, since demand paging only loads pages specified by the executing process. Demand paging leaves more space in main memory, since added data is only moved there on as-needed basis.

Disadvantages

• Disadvantages of demand paging include increased load time when a page is loaded or accessed for the first time. Demand paging also increases vulnerability to timing attacks, or attacks in which an attacker attempts to analyze the time it takes to execute cryptographic, or coded, mathematical computations called algorithms necessary to call up computer files.

Read more: http://www.ehow.com/facts_7241892_demand-paging_.html#ixzz2plqZ1KTW