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cache2 - Improving Cache Performance Average memory-access...

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Improving Cache Performance Average memory-access time = Hit time + Miss rate x Miss penalty (ns or clocks) 1. Reduce the miss rate, 2. Reduce the miss penalty, or 3. Reduce the time to hit in the cache. CSE 240A Dean Tullsen Reducing Misses Classifying Misses: 3 Cs How To Measure Compulsory —The first access to a block is not in the cache, so the block must be brought into the cache. These are also called cold start misses or first reference misses . Misses in infinite cache N l Capacity —If C is the size of the cache (in blocks) and there have been more than C unique cache blocks accessed since this cache was last accessed. Non-compulsory misses in size X fully associative cache Conflict —Any miss that is not a compulsory miss or capacity miss must be a byproduct of the cache mapping algorithm. A conflict miss occurs because too many acti e blocks are mapped to the same cache set Non-compulsory, non-capacity i active blocks are mapped to the same cache set. misses CSE 240A Dean Tullsen 3Cs Absolute Miss Rate CSE 240A Dean Tullsen How To Reduce Misses? Compulsory Misses? C i Mi ? Capacity Misses? Conflict Misses? What can the compiler do? CSE 240A Dean Tullsen
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