Alessandro Arnone aarnone

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

	0⃣ 0, keycap, zero
	1⃣ 1, number, one
	🕜 1, 30, clock, time, one, thirty, 1:30, one-thirty
	🕐 1, clock, time, one, 00, o’clock, 1:00, one o’clock
	2⃣ 2, number, two
	🕝 2, 30, clock, time, two, thirty, 2:30, two-thirty
	🕑 2, clock, time, two, 00, o’clock, 2:00, two o’clock
	3⃣ 3, keycap, three
	🕞 3, 30, three, clock, time, thirty, 3:30, three-thirty
	🕒 3, three, clock, time, 00, o’clock, 3:00, three o’clock