[理工] os 恐龍版習題 memory

看板Grad-ProbAsk作者rnbjacky (浪漫A大調)時間15年前 (2011/02/24 20:51)推噓3(3推 0噓 5→)

留言8則, 4人參與討論串1/1

Consider a demand-paging system with a paging disk that has an average access and transfer time of 20milliseconds.Addresses are translated through a page table inmainmemory, with an access time of 1microsecond per memory access. Thus, eachmemory reference through the page table takes two accesses. To improve this time, we have added an associativememory that reduces access time to one memory reference, if the page-table entry is in the associative memory. Assume that 80 percent of the accesses are in the associative memory and that, of the remaining, 10 percent (or 2 percent of the total) cause page faults.What is the effective memory access time? 我列的式子是 o.8 * 1 us + o.2 * ( 0.9 * 2 us + 0.1 *( 2 us + 20 ms ) ) 假設存取associative memory 時間是 0 請問哪邊有問題? 算不出他給的答案 (0.8) × (1 usec ) + (0.1) × (2 usec) + (0.1) × (5002 usec) 希望版上的大大可以幫忙解惑!! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 221.120.0.82

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fxac

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hunter0904

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rnbjacky

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