Back-of-the-envelop Flashcards
1
Q
L1 cache reference
A
0.5 ns
2
Q
Branch mispredict
A
5 ns
3
Q
L2 cache reference
A
7 ns
4
Q
Mutex lock/unlock
A
100 ns
5
Q
Main memory reference
A
100 ns
6
Q
Compress 1K bytes with Zippy
A
10,000 ns = 10 µs
7
Q
Send 2K bytes over 1 Gbps network
A
20,000 ns = 20 µs
8
Q
Read 1 MB sequentially from memory
A
250,000 ns = 250 µs
9
Q
Round trip within the same datacenter
A
500,000 ns = 500 µs
10
Q
Disk seek
A
10,000,000 ns = 10 ms
11
Q
Read 1 MB sequentially from the network
A
10,000,000 ns = 10 ms
12
Q
Read 1 MB sequentially from disk
A
30,000,000 ns = 30 ms
13
Q
Send packet CA (California) ->Netherlands->CA
A
150,000,000 ns = 150 ms
14
Q
ns = nanosecond, µs = microsecond, ms = millisecond
1 ns = 10^-9 seconds
1 µs= 10^-6 seconds = 1,000 ns
1 ms = 10^-3 seconds = 1,000 µs = 1,000,000 ns
A
