任何程序员应该记住的性能指标
Numbers Everyone Should Know
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 0.1 us
Compress 1K bytes with Zippy 3,000 ns 3 us 0.003 ms
Send 2K bytes over 1 Gbps network 20,000 ns 20 us 0.02 ms
Read 1 MB sequentially from memory 250,000 ns 250 us 0.25 ms
Round trip within same datacenter 500,000 ns 500 us 0.5 ms
Disk seek 10,000,000 ns 10,000 us 10 ms
Read 1 MB sequentially from disk 20,000,000 ns 20,000 us 20 ms
Send packet CA->Netherlands->CA 150,000,000 ns 150,000 us 150 ms