[理工] [計組]-記憶體

看板Grad-ProbAsk作者 (心安即自在)時間15年前 (2010/03/19 17:01), 編輯推噓4(406)
留言10則, 4人參與, 最新討論串1/1
題目:A computer system uses two levels of cache L1 and L2. Level L1 is accessed in one clock cycle and supplies the data in case of an L1 hit. For an L1 miss,occurring 3% of the time, L2 is consulted. An L2 hit incurs a penalty of 10 clock cycles while an L2 miss implies a 100-cycle penalty. (2)If we were to model the two-level cache system as a single cache, what miss rate and miss penalty should we use? (L2's local miss rate is 25% 且pipeline CPI with no cache miss is 1) 手邊的答案是: miss rate = 3% * 25% = 0.75% miss penalty=1+10+100 =111clock 問題: 為什麼miss penalty 是111呀?? 麻煩幫我解答一下 感謝!! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 140.134.213.201

03/19 17:24, , 1F
有點怪@@
03/19 17:24, 1F

03/19 19:59, , 2F
恩 挺怪的!
03/19 19:59, 2F

03/19 20:24, , 3F
請問一下這是哪年哪一間的考題阿??
03/19 20:24, 3F

03/19 20:45, , 4F
95台科大電子的計組
03/19 20:45, 4F

03/19 21:35, , 5F
我覺得應該是100 cycle說..XD 你呢?
03/19 21:35, 5F

03/19 22:12, , 6F
我手邊有另一種版本的答案是給110 XD
03/19 22:12, 6F

03/20 12:42, , 7F
L2 miss要花100搬到L2中,L1要花10在L2 hit並搬到L1中
03/20 12:42, 7F

03/20 12:43, , 8F
CPU要花1在L1中Hit並拿來用~所以100+10+1=111
03/20 12:43, 8F

03/20 12:43, , 9F
可以這樣解釋嗎……
03/20 12:43, 9F

09/29 16:25, , 10F
樓上正解吧,因為HIT就1 失敗從MEM到CPU確實111
09/29 16:25, 10F
文章代碼(AID): #1Beprhdu (Grad-ProbAsk)