※ 引述《yesa315 (XD)》之铭言： : Suppose the Linux scheduler chooses the process with the most credits for : run, and if no runnable processes can be chosen, the recrediting operation is : performed according to the following rule for every process in the system: : credits=credits/2+priority : For each timr slice, currently running process will lose one credit. : When the credits reach zero, it is suspended. According to the above : description, which of the following statements is correct? "假设priority number大的 priority 愈高" <= 这是问题点 假设初始情况: P1-P2-P3 同时进入 Process Priority Credit P1 2 2 P2 2 2 P3 4 4 根据 Scheduler 会先挑 P3 来做 : (a)this credit system gives high priority to CPU-bound processes 这要看 CPU-bound 的 priority 是高或低 , 通常是低 假设 P2 是 CPU-bound P3 连续用了 2 个 time slice 後 Process Priority Credit P1 2 2 P2 2 2 P3 4 2 根据 公式 新的 credit 为 Process Priority Credit P1 2 3 P2 2 3 P3 4 5 还是挑 P3 来做... CPU-bound priority 并没有提高 : (b)the scheduling will exhibit short response time 由上可知 high-priority (P3 如 I/O bound) 的 response time 会缩短 : (c)interactive processes will receive fewer credits than non-I/O bound : processes 这要看 CPU bound process 与 interactive process 谁的 priority 高 , 通常是 interactive 较高 则 interactive process priority number 较大 , credit 较多 : (d)nine of the above : 答案有人写 D 也有人写 B 但我都不太了解题目意义 : 可以请高手指导一下吗?? 谢谢 答案选 (b) 但问题就在於 "假设 priority number 大的 代表 higher priority" 是否正确... 课本里提到 linux 是用 number 小的代表 higher priority 这样的话...(a) (c) 都对 -- --

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