G loops reuse spatial locality locality in space if an

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Unformatted text preview: me): If an item is referenced, it emporal If will tend to be referenced again soon (e.g., loops, reuse) – Spatial Locality (Locality in Space): If an item is referenced, items whose addresses are close by tend to be referenced soon (e (e.g., straight-line code, array access) straight array • Last 30 years, HW relied on locality for memory perf. P $ Some material is adapted from D. Culler & D. Patterson (UCB) MEM S. Ziavras Levels of the Memory Hierarchy (Uniprocessor) Capacity Access Time Cost CPU Registers 2GHz 100s Bytes 300 – 500 ps (0.3-0.5 ns) L1 and L2 Cache 10s-100s K Bytes ~1 ns - ~10 ns $1000s/ GByte Registers Instr. Operands L1 Cache Blocks Disk 10s T Bytes, 10 ms (10 (10,000,000 ns) ~ $1 / GByte Tape infinite sec-min ~$1 / GByte Upper Level prog./compiler 1-8 bytes faster cache cntl 32-64 bytes L2 Cache Blocks Main Memory G Bytes 80ns- 200ns ~ $100/ GByte Staging Xfer Unit cache cntl 64-128 bytes Memory Pages OS 4K-8K bytes Files user/operator Mbytes Disk Tape Some material is...
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