[理工] [OS]99中山資工

看板Grad-ProbAsk作者jim055006 (好崩潰)時間14年前 (2012/01/17 15:33)推噓1(1推 0噓 7→)

留言8則, 1人參與討論串1/2 (看更多)

(1) [CPU Scheduling] Consider a system running ten I/O-bound tasks and one CPU-bound task. Assume that the I/O-bound tasks issue an I/O operation once for every millisecond of CPU computing and that each I/O operation takes 10 milliseconds to complete. Also assume that the context switching overhead is 0.1 milliseconds and that all processes are long-running tasks. What is the CPU utilization for a Round-robin scheduler when: (a) The time quantum is 1 millisecond (5%) (b) The time quantum is 10 milliseconds (5%) 這是恐龍本後面的練習題我也看了解答了可是我還是看不懂為什麼答案是 (a)1/1.1*100=91% (b)20/21.1*100=94% -------------------------------------------------------------------------------- (2) [File-System Implermentation] Consider a file system on a disk that has both logical and physical block sizes of 512 bytes. Assume that the information about each file is already in memory. For each of the three allocation strategies (contiguous, linked, and indexed). answer these questions: (a) How is the logical-to-physical address mapping accomplished in this system? (For the indexed allocation, assume that a file is always less than 512 blocks long.) (b) If we are currently at logical block 10 (the last block accessed was block 10) and want to access logical block 4, how many physical blocks must be read from the disk? 這題我看到板上有蠻多人問的可是好像都沒有很多人回應所以我想在po問一次而且我看恐龍解答也寫得很簡易所以也是看不太懂以上兩題希望大家可以慷慨解囊一下鋼溫!!! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 223.143.134.206

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