Consider a system that implements demand paging without a TLB. The single-level page table is held in memory, and we assume that there are no free frames. Each memory access requires 100 nanoseconds. It takes 6 additional milliseconds to handle a page fault if the victim page is not “dirty” or 12 additional milliseconds if the victim page is “dirty”. Experiments show that the probability of page faulting is 0.00003 (i.e., 0.003% chance) and that the average memory access time is 400ns. What is the percent chance that a page is dirty at the time it is evicted? Hint: Call the “being dirty” probability d and write a simple equation that gives the average data access time as a function of d. Solve for d (the result should be a number between 0 and 1, which you then convert to a percentage).
Consider a system that implements demand paging without a TLB. The single-level page table is held in memory, and we assume that there are no free frames. Each memory access requires 100 nanoseconds. It takes 6 additional milliseconds to handle a page fault if the victim page is not “dirty” or 12 additional milliseconds if the victim page is “dirty”.
Experiments show that the probability of page faulting is 0.00003 (i.e., 0.003% chance) and that the average memory access time is 400ns.
What is the percent chance that a page is dirty at the time it is evicted?
Hint: Call the “being dirty” probability d and write a simple equation that gives the average data access time as a function of d. Solve for d (the result should be a number between 0 and 1, which you then convert to a percentage).
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