5. Difference between resident set management and page replacement policy.

The operating system has to decide how much maiun memory to allocate to a particular process. As with paged virtual memory. It may not be possible to bring all pages of a process into main memory to prepare it for execution, several factors must be considered, such as
More processes can reside in memory at any given time when each process is allocated to a small amount of memory. If small number of pages of a process are in main memory, then the rate of page faults will be rather high despite of the principle of locality. According to the principle of locality beyond a certain size, additional allocation of main memory to a particular process will have no noticeable effect on the page fault rate for that process.
    A fixed allocation policy gives a process to a fized number of frames in main memory at the intital load time to execute and this is determined based on the type of process or on guidance from programmer or system manager. A variable allocation policy allows the number of page frames allocated to a process to be varied over the lifetime of the process.

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