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@chetan
Forked from hellerbarde/latency.markdown
Created May 31, 2012 13:57
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Latency numbers every programmer should know
L1 cache reference 0.5 ns
Branch mispredict 5 ns
L2 cache reference 7 ns
Mutex lock/unlock 25 ns
Main memory reference 100 ns
Compress 1K bytes with Zippy 3,000 ns 3 µs
Send 2K bytes over 1 Gbps network 20,000 ns 20 µs
Read 1 MB sequentially from memory 250,000 ns 250 µs
Round trip within same datacenter 500,000 ns 0.5 ms
Disk seek 10,000,000 ns 10 ms
Read 1 MB sequentially from disk 20,000,000 ns 20 ms
Send packet CA->Netherlands->CA 150,000,000 ns 150 ms
By Jeff Dean (http://research.google.com/people/jeff/):
Lets multiply all these durations by a billion:
L1 cache reference 0.5 s One Heart Beat (0.5 s)
Branch mispredict 5 s Yawn
L2 cache reference 7 s Long Yawn
Mutex lock/unlock 25 s ?
Main memory reference 100 s Brushing your teeth
Compress 1K bytes with Zippy 50 min One episode of a TV show (including ad breaks)
Send 2K bytes over 1 Gbps network 5.5 hr Flight duration from Hawaii to Utah
Read 1 MB sequentially from memory 2.9 days A long weekend.
Round trip within same datacenter 5.8 days A medium vacation
Disk seek 16.5 weeks ?
Read 1 MB sequentially from disk 7.8 months ?
Send packet CA->Netherlands->CA 4.8 years ?
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