时间访问代价

记录一下，方便以后查询

Operation	Time
L1 cache reference 访问一级缓存	0.5 ns
Branch mispredict(分支预测失败)	5 ns
L2 cache reference 访问二级缓存	7 ns
Mutex lock/unlock 互斥锁\解锁	100 ns
Main memory reference 访问主存	100 ns
Compress 1K bytes with Zippy 压缩1k字节	10,000 ns/0.01ms
Send 2K bytes over 1 Gbps network 在1Gbps的网络上发送2k字节	20,000 ns/0.02ms
Read 1 MB sequentially from memory 从主存中顺序读取1MB	250,000 ns/0.25ms
Round trip within same datacenter 从数据中心内部往返一次	500,000 ns/0.5ms
Disk seek 磁盘搜索/寻道	10,000,000 ns /10ms
Read 1 MB sequentially from network 从网络上顺序读取1M数据	10,000,000 ns/10ms
Read 1 MB sequentially from disk 从磁盘中顺序读出1MB数据	30,000,000 ns /30ms
Send packet CA->Netherlands->CA 一次远程访问时间	150,000,000 ns/150ms