top 과 같이 mysql을 모니터링 하는 툴이 있군요. 아래는 내용입니다.

About

mytop is a console-based (non-gui) tool for monitoring the threads and overall performance of MySQL 3.22.x, 3.23.x, and 4.x servers. It runs on most Unix systems (including Mac OS X) which have Perl, DBI, and Term::ReadKey installed. And with Term::ANSIColor installed you even get color. If you install Time::HiRes, you\ll get good real-time queries/second stats. As of version 0.7, it even runs on Windows (somewhat).

http://jeremy.zawodny.com/mysql/mytop/

그림에서 Key Efficiency가 낮게 나타나면 key buffer크기를 크게 늘려야 한다는 군요.