Latency Numbers

Latency Comparison Numbers (~2012)

Sourced from Latency Numbers Every Programmer Should Know | GitHub

Item	ns	us	ms	more
L1 cache reference	0.5
Branch mispredict	5
L2 cache reference	7			14x L1 cache
Mutex lock/unlock	25
Main memory reference	100			20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy	3,000	3
Send 1K bytes over 1 Gbps network	10,000	10
Read 4K randomly from SSD*	150,000	150		~1GB/sec SSD
Read 1 MB sequentially from memory	250,000	250
Round trip within same datacenter	500,000	500
Read 1 MB sequentially from SSD*	1,000,000	1,000	1	~1GB/sec SSD, 4X memory
Disk seek	10,000,000	10,000	10	20x datacenter roundtrip
Read 1 MB sequentially from disk	20,000,000	20,000	20	80x memory, 20X SSD
Send packet CA->Netherlands->CA	150,000,000	150,000	150

note that,

• 1 ns = 10^-9 seconds

• 1 us = 10^-6 seconds = 1,000 ns

• 1 ms = 10^-3 seconds = 1,000 us = 1,000,000 ns

--

Credit

By Jeff Dean: http://research.google.com/people/jeff/ Originally by Peter Norvig: http://norvig.com/21-days.html#answers

Contributions

'Humanized' comparison: https://gist.github.com/hellerbarde/2843375 Visual comparison chart: http://i.imgur.com/k0t1e.png