Latency Numbers Every Programmer Should Know

Latency Comparison Numbers


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L1 cache reference                            0.5 ns


Branch mispredict                             5   ns


L2 cache reference                            7   ns             14x L1 cache


Mutex lock/unlock                            25   ns


Main memory reference                       100   ns             20x L2 cache, 200x L1 cache


Compress 1K bytes with Zippy              3,000   ns


Send 1K bytes over 1 Gbps network        10,000   ns    0.01 ms


Read 4K randomly from SSD*              150,000   ns    0.15 ms


Read 1 MB sequentially from memory      250,000   ns    0.25 ms


Round trip within same datacenter       500,000   ns    0.5  ms


Read 1 MB sequentially from SSD*      1,000,000   ns    1    ms  4X memory


Disk seek                            10,000,000   ns   10    ms  20x datacenter roundtrip


Read 1 MB sequentially from disk     20,000,000   ns   20    ms  80x memory, 20X SSD


Send packet CA->Netherlands->CA     150,000,000   ns  150    ms


 


Notes


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1 ns = 10-9 seconds


1 ms = 10-3 seconds


* Assuming ~1GB/sec SSD



Reference:

https://www.google.com/fusiontables/DataSource?snapid=S523155yioc