Numbers Programmers should know

Latency Numbers

Access TypeTimeConverted Time
CPU cycle.3 nano secs1 secs
CPU L1 cache1 nano secs3 secs
CPU L2 cache3 nano secs9 secs
CPU L3 cache13 nano secs43 secs
Main memory (RAM)120 nano secs6 mins
SSD150 micro secs6 day
HDD10 milli secs12 months
San Franscio to New York40 milli secs4 years
San Fransisco to Australia183 milli secs19 years


Latency Key Takeways

  • Avoid network cache whenever possible
  • Replicate data across data centre for disaster recovery as well as performance
  • Use CDNs to reduce latenc
  • Keep frequently accessed data in memory if possible rather than seeking from disk, caching

Map Reduce IRL

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