DEV Community

Saad Alem
Saad Alem

Posted on

Numbers that every computer engineer should know, according to Jeff Dean

L1 cache reference: 0.5 ns
Branch mispredict: 5 ns
L2 cache reference: 7 ns
Mutex lock/unlock: 100 ns
Main memory reference: 100 ns
Compress 1K bytes with Zippy: 10,000 ns
Send 2K bytes over 1 Gbps network: 20,000 ns
Read 1 MB sequentially from memory: 250,000 ns
Round trip within same datacenter: 500,000 ns
Disk seek: 10,000,000 ns
Read 1 MB sequentially from network: 10,000,000 ns
Read 1 MB sequentially from disk: 30,000,000 ns
Send packet CA->Netherlands->CA: 150,000,000 ns

(1 ns = 1 * 10^-9 s)

These numbers have been updated by others :
https://colin-scott.github.io/blog/2012/12/24/latency-trends/

Top comments (0)