The following memory addresses are used consecutively by a running program (from
ID: 3571884 • Letter: T
Question
The following memory addresses are used consecutively by a running program (from left to right, shown in decimal). Note that the followings are memory address not block number:
520, 400, 380, 540, 816, 204, 1348, 200, 440, 140, 1064, 44, 196, 404, 180
In each of the following cache structures, compute the number of hits, misses and the final values stored in each cache location (show finally which block of memory is in each cache block). Each word is 4-bytes and the memory size is 8Kbyte
(a) Direct-mapped cache with 32-word blocks and a total size of cache is 128 words of data (b) 2-way set associative cache with 32-word blocks and a total size of cache is 128 words of
Explanation / Answer
a) Here in Direct mapped cache we have 32 words block and total cache size is 128 hence number of cache blocks would be 128/32 = 4 blocks which means
Cache 0 – 0,..,31 128,…,159 257,..,288 385,…,416 513,.., 544 641,…, 672 769,..,800 897,..,928 1025,..,1056 1153,…,1184 1281,…1312
Cache 1 - 32,..,63 160,…,191 289,…,320 417,…,448 545,.., 576 673,…,704 801,..,832 929,..,960 1057,..,1088 1185,…,1216 1313,…1344
Cache 2 – 64,..,95 192,..,223 321,..,352 449,..,480 577,…,608 705,…, 736 833,…,864 961,..,992 1089,…,1120 1217,…,1248 1345,…,1376
Cache 3 - 96,..,127 224,…,256 353,…,384 481,…,512 609,…,640 737,…,768 865,….,896 993,..,1024 1121,….,1152 1249,…,1280
Address
Hit/Miss
Cache description
520
Miss
Fetches 520 from cache 0 513,…544
400
Miss
Fetches 400 from cache 0 385,…416
380
Miss
Fetches 380 from cache 3 , 353,..384
540
Miss
Fetched 540 from cache 0 , 513,…544
826
Miss
Fetches from cache 1 801,…832
204
Miss
Fetches 204 from cache 2 192,223
1348
Miss
Fetches 1348 from cache 2 1345,..1376
200
Miss
Fetches 200 from cache 2, 192,…223
440
Miss
Fetches 440 from cache 1, 417,…448
140
Miss
Fetches 140 from cache 0, 128,…159
1064
Miss
Fetches 1064 from Cache 1 1057,…,1088
44
Miss
Fetches 44 from cache 1 32,…63
196
Hit
Already in cache 2
404
Miss
Fetches 404 from cache 0 385,…416
180
Miss
Fetches 180 from cache 1 160,..191
Address
Hit/Miss
Cache description
520
Miss
Fetches 520 from cache 0 513,…544
400
Miss
Fetches 400 from cache 0 385,…416
380
Miss
Fetches 380 from cache 3 , 353,..384
540
Miss
Fetched 540 from cache 0 , 513,…544
826
Miss
Fetches from cache 1 801,…832
204
Miss
Fetches 204 from cache 2 192,223
1348
Miss
Fetches 1348 from cache 2 1345,..1376
200
Miss
Fetches 200 from cache 2, 192,…223
440
Miss
Fetches 440 from cache 1, 417,…448
140
Miss
Fetches 140 from cache 0, 128,…159
1064
Miss
Fetches 1064 from Cache 1 1057,…,1088
44
Miss
Fetches 44 from cache 1 32,…63
196
Hit
Already in cache 2
404
Miss
Fetches 404 from cache 0 385,…416
180
Miss
Fetches 180 from cache 1 160,..191
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