様々なレイテンシ
いま話題のレイテンシ.数値に対する感覚は重要だ.
Latency numbers every programmer should know — Gist
L1 cache reference ......................... 0.5 ns Branch mispredict ............................ 5 ns L2 cache reference ........................... 7 ns Mutex lock/unlock ........................... 25 ns Main memory reference ...................... 100 ns Compress 1K bytes with Zippy ............. 3,000 ns = 3 µs Send 2K bytes over 1 Gbps network ....... 20,000 ns = 20 µs Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs Round trip within same datacenter ...... 500,000 ns = 0.5 ms Disk seek ........................... 10,000,000 ns = 10 ms Read 1 MB sequentially from disk .... 20,000,000 ns = 20 ms Send packet CA->Netherlands->CA .... 150,000,000 ns = 150 ms