[理工] [OS]-Thrashing

看板Grad-ProbAsk作者 (123)時間14年前 (2010/02/12 23:30), 編輯推噓2(2推 0噓 19→)
留言21則, 6人參與, 最新討論串1/1
Which of following conditions would necessarily present a system that is thrashing (A)Paging disk is nearly 100% active (B)CPU is 100% busy (C)CPU is 100% idle (D)Some processes are blocked much of the time 請問位啥 C不能選，而且D可以選 答案為AD -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 220.138.110.105
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02/12 23:31, , 1F
我知道thrashing IO Disk會異常忙碌，可是CPU不是
02/12 23:31, 1F
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02/12 23:31, , 2F
利用度低嗎？
02/12 23:31, 2F
推
02/12 23:53, , 3F
CPU並不是100% IDLE他還是有要處理被SWAP IN的 PROCESS
02/12 23:53, 3F
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02/12 23:53, , 4F
也不可能100%BUSY 因為處理一小段時間後就被SWAP OUT
02/12 23:53, 4F
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02/13 00:17, , 5F
D會不會是因為沒啥process complete，所以資源無法釋放
02/13 00:17, 5F
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02/13 00:19, , 6F
導致有些process就要被block等待資源
02/13 00:19, 6F
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02/13 00:20, , 7F
那請問D選項呢？這題我有點搞不清楚，他是問哪些情況
02/13 00:20, 7F
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02/13 00:21, , 8F
會發生在thrashing，還是哪些情況發生代表thrashing發
02/13 00:21, 8F
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02/13 00:22, , 9F
生
02/13 00:22, 9F
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02/13 00:23, , 10F
解答是說因為page fault發生，而要等IO運作完成
02/13 00:23, 10F
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02/13 00:23, , 11F
而io很慢所以block很久
02/13 00:23, 11F
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02/13 00:28, , 12F
哪些情況發生代表thrashing發生
02/13 00:28, 12F
推
02/13 00:33, , 13F
page fault不斷發生，造成系統大部分的時間都在處理頁替換
02/13 00:33, 13F
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02/13 00:36, , 14F
他問的是trashing一定會出現哪些現象
02/13 00:36, 14F
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02/13 00:40, , 15F
兩種都有人說= =
02/13 00:40, 15F
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02/13 00:41, , 16F
我覺得比較像是aassxxzz大大說的
02/13 00:41, 16F
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02/13 00:44, , 17F
這是充要吧...
02/13 00:44, 17F
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02/13 00:45, , 18F
我收回樓上的話XD
02/13 00:45, 18F
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02/13 00:48, , 19F
這是文字遊戲嘛= =
02/13 00:48, 19F
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02/13 04:01, , 20F
C不能選很簡單阿CPU 100% idle又不代表一定thrashing
02/13 04:01, 20F
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02/13 04:02, , 21F
D 可以選 aass大說的很有道理
02/13 04:02, 21F
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