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Os doubt

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A demand paging system requires Sending trap to OS, bring the new page from LAS to PAS,updating page tables,then signaling CPU to restart the instruction time 125 time units if page is not dirty and 400 times units of page fault service time if it is a dirty page. Memory access time is 10 time units. The probability of a page fault is m . In case of page fault, the probability of page being dirty is m.

It is observed that average access time is 50 time units. Then, the value of m is ______? [upto four decimal places]

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Given  page fault service time(PS) = 125(no dirty page

         page fault service time(PS) =400(if there is dirty page in which we have to copy and then load page so it take more time compare to no dirty page replacement)

probability of page fault =m

probability of being dirty is =m


 

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