latency-numbers

latency.md

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

SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns  = 250 µs

Round trip within same datacenter ...... 500,000 ns  = 0.5 ms

Read 1 MB sequentially from SSD* ..... 1,000,000 ns  =   1 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

Assuming ~1GB/sec SSD

Visual chart provided by ayshen

Data by Jeff Dean

Originally by Peter Norvig