google 工程師Jeff Dean 首先在他關於分布式系統的ppt文檔列出來的，到處被引用的很多。
1納秒等於10億分之一秒，= 10 ^ -9 秒
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Numbers Everyone Should Know
| L1 cache reference 讀取CPU的一級緩存 | 0.5 ns |
| Branch mispredict(轉移、分支預測) | 5 ns |
| L2 cache reference 讀取CPU的二級緩存 | 7 ns |
| Mutex lock/unlock 互斥鎖\解鎖 | 100 ns |
| Main memory reference 讀取內存數據 | 100 ns |
| Compress 1K bytes with Zippy 1k字節壓縮 | 10,000 ns |
| Send 2K bytes over 1 Gbps network 在1Gbps的網絡上發送2k字節 | 20,000 ns |
| Read 1 MB sequentially from memory 從內存順序讀取1MB | 250,000 ns |
| Round trip within same datacenter 從一個數據中心往返一次，ping一下 | 500,000 ns |
| Disk seek 磁盤搜索 | 10,000,000 ns |
| Read 1 MB sequentially from network 從網絡上順序讀取1兆的數據 | 10,000,000 ns |
| Read 1 MB sequentially from disk 從磁盤里面讀出1MB | 30,000,000 ns |
| Send packet CA->Netherlands->CA 一個包的一次遠程訪問 | 150,000,000 ns |