[理工] OS time-sharing 恐龍原文描述的問題

看板Grad-ProbAsk作者 (ㄚ冰)時間8年前 (2017/11/10 21:41), 8年前編輯推噓2(209)
留言11則, 2人參與, 8年前最新討論串1/1
如果你手邊有書的話 9/e page.20 最下面 In a time-sharing system, the OS must ensure reasonable response time. This goal is sometimes accomplished through swapping, whereby processes are swapped in and out of main memory to the disk. A more common method for ensuring reasonable response time is virtual memory,a technique that allows the execution of a process that is not completely in memory. The main advantage of the virtual-memory scheme is that it enables users to run programs that are larger than actual physical memory. Futher, it abstracts main memory into a large, uniform array of storage, separating logical memory as view by the user from physical memory. 我記得之前有一題多選題 有一個選項抄這邊前兩三行的 不過他把 response time 改成 turnaround time 結果我還想說是因為swap不能改善時間 然後就看到這段話 所以說為什麼swap或是virtual memory可以改善response?? -- ※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 134.208.0.169 ※ 文章網址: https://www.ptt.cc/bbs/Grad-ProbAsk/M.1510321318.A.7DD.html ※ 編輯: TMDTMD2487 (134.208.0.169), 11/10/2017 21:42:51 ※ 編輯: TMDTMD2487 (134.208.0.169), 11/10/2017 21:43:21

11/10 22:37, 8年前 , 1F
我想是因為 Time sharing 要求極短暫的response time 才
11/10 22:37, 1F

11/10 22:37, 8年前 , 2F
能在不同使用者之間切換,當使用者在執行程式時只要放部
11/10 22:37, 2F

11/10 22:37, 8年前 , 3F
分程式在MEM中,以縮短search 跟 compare time ,就算被sw
11/10 22:37, 3F

11/10 22:37, 8年前 , 4F
ap到Disk時間很長,反正是IO 切到其他process跑就好了
11/10 22:37, 4F

11/11 07:51, 8年前 , 5F
我認為是 若是需要整個swap in&out 需要很久
11/11 07:51, 5F

11/11 07:52, 8年前 , 6F
但virtual memory容許部分載入 就可以恢復執行 會快的多
11/11 07:52, 6F

11/11 07:52, 8年前 , 7F
就response time 而言
11/11 07:52, 7F

11/11 07:59, 8年前 , 8F
抱歉搞錯原po問題
11/11 07:59, 8F

11/11 08:01, 8年前 , 9F
若不用swap或virtual mem,當memory space不足時 user 就
11/11 08:01, 9F

11/11 08:01, 8年前 , 10F
必須等別人的process跑完才可以換他的,這就不是reasonable
11/11 08:01, 10F

11/11 08:04, 8年前 , 11F
response time
11/11 08:04, 11F
謝兩位大概知道為什麼了! ※ 編輯: TMDTMD2487 (114.136.168.188), 11/11/2017 08:20:56
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