[理工] 計組 TLB

[PTT007 (鍵盤007)]

A virtual memory system often implements a TLB to speed up the
virtual-to-physical address translation. A TLB has the following characteristics. Assume each
TLB entry has a valid bit, a dirty bit, a tag, and the page number. Determine the exact total
number of bits to implement this TLB.

-It is direct-mapped.
-It has 16 entries.
-The page size is 4K bytes.
-The virtual address space is 4G bytes.
-The physical memory is 1G bytes.

求解

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推 A4P8T6X9:(1+1+16+18)*16
→ PTT007:我的答案跟你一樣，但解答給(1+1+18+20)*16
※ 編輯: PTT007          來自: 220.136.111.245      (01/04 13:30)
推 patabon:VA是32bit PA是30bit offset是12bit 減下來不是18.20嗎
→ patabon:還是我想法錯了 @@
→ A4P8T6X9:direct代表都有固定地方，所以需要index，才會覺得需要
→ A4P8T6X9:把20在扣4，剩下當tag，因為TLB通常都是用full associate
→ A4P8T6X9:的，所以才平常的tag就是全部的虛擬頁碼，換成這樣應該要
→ A4P8T6X9:扣。
推 patabon:感謝樓上解釋，看到TLB都會想到直接用full associative
→ patabon:有指定direct-mapped那的確要扣Index才合理 xd
推 leosnake:一樓正解 :)