[OS] CPU utilization

看板Grad-ProbAsk作者garnettooo (絕代風華賈奈特)時間8年前 (2017/05/17 16:36)推噓2(2推 0噓 8→)

留言10則, 2人參與討論串1/2 (看更多)

還想請問大家這題的解析，因為根據題目所提供的情況， Consider the system running ten 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 millisecond to complete. Also assume that the context switching overhead is 0.1 millisecond and that all processes are long-running tasks. What is the CPU utilization for RR scheduler when: (1)time quantum=1 millisecond (2)time quantum= 10 millisecond 可以了解CPU burst(T)=1, I/O=10,context switch=0.1 (1)第一題沒有問題，因為T=Q,所以CPU utilization=T/S+T=1/1+0.1=1/1.1 (2)第二題我就不太了解為何會有20,畢竟Q=10,Q>T,所以應該是T/S+T=1/1+0.1, 為何會是答案所給的20/21.1呢？ -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 140.118.135.18 ※ 文章網址: https://www.ptt.cc/bbs/Grad-ProbAsk/M.1495010164.A.C64.html

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nakabin

05/17 19:33, , 1^F

05/17 19:33, 1^F

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nakabin

05/17 19:33, , 2^F

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nakabin

05/17 19:33, , 3^F

05/17 19:33, 3^F