On a hidden storage space for provisions weapons

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Unformatted text preview: re 2 Duo: Bandwidth 2 Bytes/cycle Latency 100 cycles Solu4on: caches Caches Main Memory University of Washington Cache     English defini?on: a hidden storage space for provisions, weapons, and/or treasures CSE defini?on: computer memory with short access ?me used for the storage of frequently or recently used instruc?ons or data (i ­cache and d ­cache) more generally, used to op?mize data transfers between system elements with different characteris?cs (network interface cache, I/O cache, etc.) Caches University of Washington General Cache Mechanics Cache 8 9 14 3 Smaller, faster, more expensive memory caches a subset of the blocks Data is copied in block ­sized transfer units Memory 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Caches Larger, slower, cheaper memory viewed as par??oned into “blocks” University of Washington General Cache Concepts: Hit Request: 14 Cache 8 9 14 3 Memory 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Caches Data in block b is needed Block b is in cache: Hit! University of Washington General Cache Concepts: Miss Request: 12 Cache 8 9 12 3 Request: 12 12 Memory 14 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Caches Data in block b is needed Block b is not in cache: Miss! Block b is fetched from memory Block b is stored in cache • Placement policy: determines where b goes • Replacement policy: determines which block gets evicted (vic:m) University of Washington Not to forget… CPU A little of super fast memory (cache$) Lots of slower Mem Caches University of Washington Memory and Caches           Cache basics Principle of locality Memory hierarchies Cache organiza?on Program op?miza?ons that consider caches Caches and Locality University of Washingt...
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