参考链接
(https://dev.mysql.com/doc/refman/5.7/en/innodb-standard-monitor.html)
其中有这样一句：
For a description of each metric reported by the Standard Monitor, refer to the Metrics chapter in the Oracle Enterprise Manager for MySQL Database User's Guide.
这边是说输出中的每个具体细项的含义可参考：
(https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-metrics.html)