Latency Numbers Every Programmer Should Know

latency.txt

Latency Comparison Numbers                      Time     Light Distance    Approximate Light Distance
--------------------------                      ----     --------------    --------------------------
L1 cache reference                            0.5 ns             0.15 m    Diagonal across your smartphone
Branch mispredict                             5   ns             1.5  m    Height of Natalie Portman
L2 cache reference                            7   ns             2.1  m    Height of Shaq   
Mutex lock/unlock                            25   ns             7.5  m    Height of a school flag pole
Main memory reference                       100   ns            30    m    Half a Manhattan city block (North/South)
Compress 1K bytes with Zippy              3,000   ns           900    m    Width of Central Park
Send 1K bytes over 1 Gbps network        10,000   ns         3,000    m    Width of Manhattan
Read 4K randomly from SSD*              150,000   ns        45,000    m    NYC to Hempstead on Long Island
Read 1 MB sequentially from memory      250,000   ns        75,000    m    NYC to Princeton/Trenton, NJ
Round trip within same datacenter       500,000   ns       150,000    m    NYC to Scranton, PA
Read 1 MB sequentially from SSD*      1,000,000   ns       300,000    m    NYC to Boston, MA
Disk seek                            10,000,000   ns     3,000,000    m    NYC to Austin, TX
Read 1 MB sequentially from disk     20,000,000   ns     6,000,000    m    NYC to Paris, France (also the diameter of the Earth)
Send packet CA->Netherlands->CA     150,000,000   ns    45,000,000    m    Once around the equator