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Unformatted text preview: blocks 1, 5, 9, and 13 would map to block 1, and so on. Notice that our example cache in Figure 6.22 uses this policy. Restrictive placement policies of this kind lead to a type of miss known as a conﬂict miss, where the cache 6.3. THE MEMORY HIERARCHY 303 is large enough to hold the referenced data objects, but because they map to the same cache block, the cache keeps missing. For example, in Figure 6.22, if the program requests block 0, then block 8, then block 0, then block 8, and so on, each of the references to these two blocks would miss in the cache at level , even though this cache can hold a total of 4 blocks. Programs often run as a sequence of phases (e.g., loops) where each phase accesses some reasonably constant set of cache blocks. For example, a nested loop might access the elements of the same array over and over again. This set of blocks is called the working set of the phase. When the size of the working set exceeds the size of the cache, the cache will experience what are known as capacity misses. In other words, the cache is just too small to handle this particular working set. Cache...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.
- Spring '10
- The American