作者luckyburgess (the one)
看板Grad-ProbAsk
標題[理工] [計組]-計憶體管理
時間Sat Oct 10 23:50:02 2009
題目:A set-assocative has a block size of four 32-bit words and a set size
of 2. The cache can accommodate a total of 128K Bytes from main memory.
The main memory size that is cacheable 4M * 32bits.
(1) Design and draw the block diagram of the cache structure.
高銘書上的解答:
2
1 block = 4 * 32bit = 4 word = 2 word
128k Byte 13
cache block 數 = ---------- = 2 block
4 word
13
2
set 數 = -------- = 4096 set
2
------------------------------
M.M 位址: | TAG | SET | WORD |
------------------------------
\ 8bit / \ 12bit /\ 2bit /
以下省略(圖的部份)
---------------------------------------------------------------------------
問題:
想問一下就是它這題是用word來當block的單位,
那假如我現在用bytes來當block的單位這樣可以嗎??
也就是offset= 4 bit, set仍是12 bit
TAG變成 24 bit (4M*32bit = 2 ^ 24 byte) - 4bit - 12bit
= 8 bit
感謝!!
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1F：推 gsrr:要以word做為block的單位,因為Cpu一次存取就是一個word. 10/11 02:03
2F：→ luckyburgess:可是有些題目的OFFSET不是都以BYTE為單位嗎?? 10/11 14:02
3F：→ luckyburgess:好混亂呀!! 10/11 14:03