How Computers Work
memory wall
CPU-vs-RAM speed gap
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The Memory HierarchyHow Computers WorkMore terms from this board
- cachesmall fast memory near the CPU
- cache linethe ~64B unit moved between levels
- DRAMmain memory (RAM)
- hit ratefraction of hits
- hit/missfound in cache / had to go slower
- latency vs bandwidthper-access delay vs throughput
- LRU/associativitythe cache's eviction policy
- MMU/page tablethe address translator
- NUMAmemory closer to some cores than others (many-socket)
- prefetchCPU guesses & preloads the next line
- spatial localityuse nearby data
- swap/pagingspilling RAM to disk when full
- temporal localityreuse soon
- TLBa cache of translations
- virtual memoryper-process address space
- working setthe memory a program touches often