Description
- (10 points) The following code is written in C, where elements within the same row are stored contiguously. Assume each word is a 32-bit integer.
for (I=0; I<8; I++) for (J=0; J<8000; J++) A[I][J]=B[I][0]+A[J][I];
- Which variable references exhibit temporal locality? (5 points)
- Which variable references exhibit spatial locality? (5 points)
- (40 points) Below is a list of 32-bit memory address references, given as word addresses:
0x03, 0xB4, 0x2B, 0x02, 0xBF, 0x58, 0xBE, 0x0E, 0xB5, 0x2C, 0xBA, 0xFD
- For each of these references, identify the tag and the cache index given a direct-mapped cache with 8 one-word blocks. Also list if each reference is a hit or a miss, assuming the cache is initially empty. (10 points)
- For each of these references, identify the tag and the cache index given a direct-mapped cache with two-word blocks and a total size of 4 blocks. Also list if each reference is a hit or a miss, assuming the cache is initially empty. (10 pints)
- You are asked to optimize a cache design for the given references. There are three direct-mapped cache designs possible, all with a total of 8 words of data: C1 has 1-word blocks, C2 has 2-word blocks, and C3 has 4-word blocks. In terms of miss rate, which cache design is the best? If the miss stall time is 35 cycles, and C1 has an access time of 2 cycles, C2 takes 3 cycles, and C3 takes 5 cycles, which is the best cache design? (20 points)
- (50 points) For a direct-mapped cache design with a 32-bit byte address, the following bits of the address are used to access the cache.
| Tag | Index | Offset |
| 31–10 | 9–5 | 4–0 |
- What is the cache block size (in words)? (5 points)
- How many blocks does the cache have? (5 points)
- What is the ratio between total bits required for such a cache implementation over the data storage bits? (5 points)
Beginning from power on, the following byte addresses for cache references are recorded.
| Address | |||||||||||
| 0x00 | 0x04 | 0x10 | 0x84 | 0xE8 | 0xA0 | 0x400 | 0x1E | 0x8C | 0xC1C | 0xB4 | 0x884 |
- (20 points) For each reference, list
- its tag, index, and offset
- whether it is a hit or a miss, and
- How many blocks were replaced (if any)?
- What is the hit ratio? (5 points)
- Show the final state of the cache, with each valid line represented as <index, tag, data>. (10 points)
