关于性能优化层面的记录

zhuan http://static.googleusercontent.com/external_content/untrusted_dlcp/research.google.com/zh-CN//people/jeff/stanford-295-talk.pdf

Numbers Everyone Should Know

L1 cache reference                             0.5 ns

Branch mispredict                              5 ns

L2 cache reference                             7 ns

Mutex lock/unlock                            100 ns

Main memory reference                        100 ns

Compress 1K bytes with Zippy              10,000 ns

Send 2K bytes over 1 Gbps network         20,000 ns

Read 1 MB sequentially from memory       250,000 ns

Round trip within same datacenter        500,000 ns

Disk seek                             10,000,000 ns

Read 1 MB sequentially from network   10,000,000 ns

Read 1 MB sequentially from disk      30,000,000 ns

Send packet CA->Netherlands->CA      150,000,000 ns