Re: [理工] [OS] 99台大資工
※ 引述《weiyung (迪西)》之銘言:
: http://ppt.cc/vVpr
: 第5題不太會算哩,想請問各位大大的答案是多少呢?
: 我自己寫是..
: (a)4+N
: (b)(2N+8)/(N+9)
: (c)NO
: (d)(2N+8)/N(N+9)
: (e)9/7
: 應該會錯很多@@
: 因為自己寫起來會覺得怪怪的>"<
: 所以還請各位大大幫忙訂正~感謝
(a)(b)(c)一致(希望我沒搞錯題目qqqq)
剩下亂解,看看就好
(d) CPI = 1/N(4+1)+2/N(4+2)+...+N/N(4+N)
= 1/N( 4(1+2+...+N) + (1^2+2^2+...+N^2) )
= 1/N( 4(N)(N+1)/2) + (N)(N+1)(2N+1) / 6)
= 2(N+1) + (N+1)(2N+1) / 6
= (N+1)(2N+13)/6
Single cycle 的CPI是(4+N)
應該是相除就是答案?
(e) 考慮Cycle沒有分一半的,無條件進位
Class 1: (4+1)/2 = 2.5 => 3 cycles
Class 2: (4+2)/2 = 3 => 3 cycles
Class 3: (4+3)/2 = 3.5 => 4 cycles
Class 4: (4+4)/2 = 4 => 4 cycles
Class 5: (4+5)/2 = 4.5 => 5 cycles
CPI = (3+3+4+4+5)/5 = 3.8
Speedup = (4+5) / 3.8*2 = 9 / 7.6
乘二是因為Clock cycle長度變長了一倍
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◆ From: 122.127.178.87
※ 編輯: ybite 來自: 122.127.178.87 (02/14 21:40)
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