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Latency numbers every programmer should know

CPU

  • L1 cache reference 0.5 ns
  • Branch mispredict 5 ns (on a bad CPU architecture you're pretty much screwed)
  • L2 cache reference 7 ns
  • Mutex lock/unlock 25 ns
  • Main memory reference 100 ns
  • Compress 1K bytes with Zippy 3,000 ns
  • Send 2K bytes over 1 Gbps network 20,000 ns
  • Read 1 MB sequentially from memory 250,000 ns
  • Round trip within same datacenter 500,000 ns

HDD

  • Disk seek 10,000,000 ns
  • Read 1 MB sequentially from disk 20,000,000 ns
  • Send packet CA->Netherlands->CA 150,000,000 ns

SSD

  • Disk seek 100,000 ns

By Jeff Dean

@esafzay

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esafzay commented Sep 23, 2016

I think these are related to network

  • Send 2K bytes over 1 Gbps network 20,000 ns
  • Round trip within same datacenter 500,000 ns
  • Send packet CA->Netherlands->CA 150,000,000 ns
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