5 Chunk size
For a given device, the product of latency and sustained bandwidth gives an idea of the size in bytes of contiguous chunks which are read or written where transfer time starts to be dominated by bandwidth rather than latency.
| Device / Link | Latency (approx) | Bandwidth (approx) | Latency × Bandwidth (“natural chunk”) |
|---|---|---|---|
| L1 cache | 1 ns | 1 TB/s | ~1 KB |
| L2 cache | 3 ns | 500 GB/s | ~1.5 KB |
| L3 cache | 10 ns | 200 GB/s | ~2 KB |
| Main memory (DRAM) | 80 ns | 50 GB/s | ~4 KB |
| NVMe SSD | 100 µs | 3 GB/s | ~300 KB |
| SATA SSD | 100 µs | 500 MB/s | ~50 KB |
| HDD | 10 ms | 200 MB/s | ~2 MB |
| 1 GbE LAN | 0.1 ms | 125 MB/s | ~12.5 KB |
| 10 GbE LAN | 0.1 ms | 1.25 GB/s | ~125 KB |
| Typical WAN | 50 ms | 50 Mb/s | ~300 KB |