컴퓨터구조 퀴즈 9
1. Find data access time in ms.
• 1024 byte sector: 7,200 RPM
• average seek time: 11ms
• transfer rate: 34MB/sec
• controller overhead: 480 Mbits/sec
average rotational latency:
0.5rotation / (7,200 / 60 )RPS = 0.0041666...sec = 4.167ms
transfer time:
sector 크기 = 1024 bytes
1KB / (34 MB/sec) = 1KB / (34,000 KB/sec) = 0.000029 sec = 0.029ms
controller overhead:
sector 크기 = 1024 bytes
1KB / (480 Mbits/sec) = 1KB / ((480/8)MB/sec) = 0.000017 sec = 0.017ms
disk access time:
average seek time + average rotational latency + transfer time + controller overhead = 11ms + 4.167ms + 0.029ms + 0.017 = 15.213
2. For a direct-mapped cache design with a 8-bit address, the following byte-addressed cache references are recorded.
①1(00000001)→②134(10000110)→③212(11010100)→④1(00000001)→
⑤135(10000111)→⑥213(11010101)→⑦162(10100010)→⑧161(10100001)→
⑨2(00000010)→⑩44(00101100)→⑪41(00101001)→⑫221(11011101)
(a) The following bits of the address are used to access the cache. Show cache accesses of 12 data.
tag 4bits, index 4bits 일때,
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | ||
| 010 | ||
| 011 | ||
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
① 1(00000001) tag : 0000, index : 0001
miss
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | ||
| 011 | ||
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
② 134(10000110) tag : 1000, index : 0110
miss
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | ||
| 011 | ||
| 100 | ||
| 101 | ||
| 110 | 1000 | 10000110 |
| 111 |
③212(11010100) tag : 1101, index : 0100
miss
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | ||
| 011 | ||
| 100 | 1101 | 11010100 |
| 101 | ||
| 110 | 1000 | 10000110 |
| 111 |
④ 1(00000001) tag : 0000, index : 0001
hit
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | ||
| 011 | ||
| 100 | 1101 | 11010100 |
| 101 | ||
| 110 | 1000 | 10000110 |
| 111 |
⑤, ⑥, ⑦, ⑧, ⑨, ⑩, ⑪, ⑫ miss
hit ratio = 1/12
(b) The following bits of the address are used to access the cache. Show cache accesses of 12 data.
tag(4) index(3), block#(1)
① 1(00000001) tag : 0000, index : 000, block# : 1
miss
| index | tag | data |
|---|---|---|
| 000 | 0000 | 00000001 |
| 001 | ||
| 010 | ||
| 011 | ||
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
② 134(10000110) tag : 1000, index : 011, block# : 0
miss
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | ||
| 011 | 1000 | 10000110 |
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
③212(11010100) tag : 1101, index : 010, block# : 0
miss
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | 1101 | 11010100 |
| 011 | 1000 | 10000110 |
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
④ 1(00000001) tag : 0000, index : 000, block# : 1
hit
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | 1101 | 11010100 |
| 011 | 1000 | 10000110 |
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
⑤135(10000111) tag: 1000, index 011, block# 1
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | 1101 | 11010100 |
| 011 | 1000 | 10000110, 10000111 |
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
⑥213(11010101) tag: 1101, index 010, block# 1
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 0000 | 00000001 |
| 010 | 1101 | 11010100, 11010101 |
| 011 | 1000 | 10000110, 10000111 |
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
⑦162(10100010) tag 1010 index 001, block# 0
| index | tag | data |
|---|---|---|
| 000 | ||
| 001 | 1010 | 10100010 |
| 010 | 1101 | 11010100, 11010101 |
| 011 | 1000 | 10000110, 10000111 |
| 100 | ||
| 101 | ||
| 110 | ||
| 111 |
⑧161(10100001)→
⑨2(00000010)→⑩44(00101100)→⑪41(00101001)→⑫221(11011101)
