joelklabo

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