google 工程师Jeff Dean 首先在他关于分布式系统的ppt文档列出来的，到处被引用的很多。
1纳秒等于10亿分之一秒，= 10 ^ -9 秒
-----------------------------------------------------------
Numbers Everyone Should Know
| L1 cache reference 读取CPU的一级缓存 | 0.5 ns |
| Branch mispredict(转移、分支预测) | 5 ns |
| L2 cache reference 读取CPU的二级缓存 | 7 ns |
| Mutex lock/unlock 互斥锁\解锁 | 100 ns |
| Main memory reference 读取内存数据 | 100 ns |
| Compress 1K bytes with Zippy 1k字节压缩 | 10,000 ns |
| Send 2K bytes over 1 Gbps network 在1Gbps的网络上发送2k字节 | 20,000 ns |
| Read 1 MB sequentially from memory 从内存顺序读取1MB | 250,000 ns |
| Round trip within same datacenter 从一个数据中心往返一次，ping一下 | 500,000 ns |
| Disk seek 磁盘搜索 | 10,000,000 ns |
| Read 1 MB sequentially from network 从网络上顺序读取1兆的数据 | 10,000,000 ns |
| Read 1 MB sequentially from disk 从磁盘里面读出1MB | 30,000,000 ns |
| Send packet CA->Netherlands->CA 一个包的一次远程访问 | 150,000,000 ns |
