The comparision of latency numbers that every programmer should know. 

Latency Comparison Numbers

 


 

Operation

Time in ns

Time in ms

Comment

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

Compress 1K bytes with Zip

3,000

   

Send 1K bytes over 1 Gbps network

10,000

0.01

 

Read 4K randomly from SSD

150,000

0.15

 

Read 1 MB sequentially from memory

250,000

0.25

 

Round trip within same datacenter

500,000

0.5

 

Read 1 MB sequentially from SSD

1,000,000

1

4X memory

Disk seek

10,000,000

10

20x datacenter roundtrip

Read 1 MB sequentially from disk

20,000,000

20

80x memory, 20X SSD

Send packet CA->Netherlands->CA

150,000,000

150

 

 

Notes


1 ns = 10^-9 seconds

1 ms = 10^-3 seconds

Assuming ~1GB/sec SSD

 

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