Latency
Latency Comparison Numbers (~2012)
| Operation | ns | µs | ms | note |
|---|---|---|---|---|
| L1 cache reference | 0.5 ns | |||
| Branch mispredict | 5 ns | |||
| L2 cache reference | 7 ns | 14x L1 cache | ||
| Mutex lock/unlock | 25 ns | |||
| Main memory reference | 100 ns | 20x L2 cache, 200x L1 cache | ||
| Compress 1K bytes with Zippy | 3,000 ns | 3 µs | ||
| Send 1K bytes over 1 Gbps network | 10,000 ns | 10 µs | ||
| Read 4K randomly from SSD* | 150,000 ns | 150 µs | ~1GB/sec SSD | |
| Read 1 MB sequentially from memory | 250,000 ns | 250 µs | ||
| Round trip within same datacenter | 500,000 ns | 500 µs | ||
| Read 1 MB sequentially from SSD* | 1,000,000 ns | 1,000 µs | 1 ms | ~1GB/sec SSD, 4X memory |
| Disk seek | 10,000,000 ns | 10,000 µs | 10 ms | 20x datacenter roundtrip |
| Read 1 MB sequentially from disk | 20,000,000 ns | 20,000 µs | 20 ms | 80x memory, 20X SSD |
| Send packet CA -> Netherlands -> CA | 150,000,000 ns | 150,000 µs | 150 ms |
Notes
- 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
2023年12月19日 / 18:51