Comment posted to
http://blog.csdn.net/biti_rainy/archive/2004/07/06/learn_oracle_20040706_1.aspx?Pending=true
http://blog.csdn.net/biti_rainy/article/details/35188

Excellent article. One suggestion: change order by misses to order by sleeps when you select from x$bh. 
The statement "gets表示总共有这么多次请求，misses表示请求失败的次数" is not accurate. Gets does not include 
Spin Gets. Besides, Steve Adams' book p.23 says if the process sleeps and wakes up later (and/or does 
this multiple times), the numbers gets, misses and spin gets will NOT be incremented any more. That's 
probably the reason people use sleeps to indirectly measure the contention to acquire latches.