akrisanov
3/11/2018 - 4:09 PM
Latency Numbers Every Programmer Should Know
Latency Numbers Every Programmer Should Know
| Task | ns | us | ms | |
|---|---|---|---|---|
| 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 |
- 1 = 10^-9 seconds
- 1 = 10^-6 seconds = 1,000 ns
- 1 ms = 10^-3 seconds = 1,000 = 1,000,000 ns