| Event | Latency | Scaled |
|---|---|---|
| 1 CPU cycle | 0.3 ns | 1 s |
| Level 1 cache access | 0.9 ns | 3 s |
| Level 2 cache access | 2.8 ns | 9 s |
| Level 3 cache access | 12.9 ns | 43 s |
| Main memory access (DRAM, from CPU) | 120 ns | 6 min |
| Solid-state disk I/O (flash memory) | 50–150 µs | 2–6 days |
| Rotational disk I/O | 1–10 ms | 1–12 months |
| Internet: San Francisco to New York | 40 ms | 4 years |
| Internet: San Francisco to United Kingdom | 81 ms | 8 years |
| Internet: San Francisco to Australia | 183 ms | 19 years |
| TCP packet retransmit | 1–3 s | 105–317 years |
| OS virtualization system reboot | 4 s | 423 years |
| SCSI command time-out | 30 s | 3 millennia |
| Hardware (HW) virtualization system reboot | 40 s | 4 millennia |
| Physical system reboot | 5 m | 32 millennia |
Table 2.2, Example Time Scale of System Latencies, from Brendan Gregg’s Systems Performance.
Time Scale of System Latencies