典型 PC 系统各种操作指令的大概时间
| execute typical instruction 执行基本指令 | 1/1,000,000,000 sec = 1 nanosec |
| fetch from L1 cache memory 从一级缓存中读取数据 | 0. 5 nanosec |
| branch misprediction 分支误预测 | 5 nanosec |
| fetch from L2 cache memory 从二级缓存获取数据 | 7 nanosec |
| Mutex lock/unlock 互斥加锁/解锁 | 25 nanosec |
| fetch from main memory 从主内存获取数据 | 100 nanosec |
| send 2K bytes over 1Gbps network 通过 1G bps 的网络发送 2K 字节 | 20,000 nanosec |
| read 1MB sequentially from memory 从内存中顺序读取 1MB 数据 | 250,000 nanosec |
| fetch from new disk location (seek) 从新的磁盘位置获取数据（随机读取） | 8,000,000 nanosec |
| read 1MB sequentially from disk 从磁盘中顺序读取 1MB 数据 | 20,000,000 nanosec |
| send packet US to Europe and back 从美国发送一个报文包到欧洲再返回 | 150 milliseconds = 150,000,000 nanosec |
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