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Every Programmer Should Know These Latency Numbers

Every Programmer Should Know These Latency Numbers

1秒=1000毫秒(ms) 
1秒=1,000,000 微秒(μs) 
1秒=1,000,000,000 纳秒(ns) 
1秒=1,000,000,000,000 皮秒(ps)
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
SSD random read ........................ 150,000 ns = 150 μs
Read 1 MB sequentially from memory ..... 250,000 ns = 250 μs
Round trip within same datacenter ...... 500,000 ns = 0.5 ms
Read 1 MB sequentially from SSD* ..... 1,000,000 ns = 1 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
posted @ 2015-06-11 00:01  程序优化  阅读(143)  评论(0编辑  收藏  举报