[理工] [OS] 99清大資工 5c interrupt
For a computer with no hardware interrupt, is it possible to
implement a multi-tasking Operating System? Please note that
the computer still provide trap and the performance of the
Operating System is not considered.
我原本以為是NO,除非確定每個JOB都有大量的system call。
但是我看洪的題庫解答卻是yes,而且理由中有一句話我覺得很奇怪:
『...自己建立logical timer,...,OS可以設定max time quantum...
且OS隨時檢查counter值,一旦為零...』
 ̄ ̄ ̄ ̄ ̄ ̄ ̄ ̄ ̄ ̄ ̄
假如CPU現在正在執行Pa,除非Pa有使用system call或發生錯誤,不然
OS應該拿不到CPU不是嗎?那它要怎麼檢查counter值?
還是我的觀念有問題~"~
有人會這題的嗎?我爬文有人在推文提到有trap就可以,可是我不太
懂為什麼。
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1.interrupt的種類:
A.硬體1.External interrupt(HW) CPU以外的周邊元件所發出的 eg. I/O complete、
I/O error、machine check
2.Internal interrupt(HW) CPU本身所引發的 eg. stack overflow、illegal command(
非法指令執行)、divided by zero(除以0)...
B.軟體
Software interrupt 當user program執行時,若需要OS提供服務,則發出此類中斷通知
OS執行對應的service routine eg. system call、trap
不合法命令和除以0,我的筆記和我查的資料都是硬體內部中斷
但是比較trap和硬體中斷的時候除以0是放在trap....
※ 編輯: worldxxi 來自: 118.160.87.87 (01/09 20:31)
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