Innodb_buffer_pool_read

> show status like  'Innodb_buffer_pool_read_%';
+---------------------------------------+--------------+
| Variable_name                         | Value        |
+---------------------------------------+--------------+
| Innodb_buffer_pool_read_ahead_rnd     | 0            |
| Innodb_buffer_pool_read_ahead         | 115434683    |
| Innodb_buffer_pool_read_ahead_evicted | 0            |
| Innodb_buffer_pool_read_requests      | 113290429682 |
| Innodb_buffer_pool_reads              | 4372247      |
+---------------------------------------+--------------+
5 rows in set (0.00 sec)

Thu Oct 24 09:32:55 2019 > 

Innodb_buffer_pool_read_requests表示read请求的次数，

Innodb_buffer_pool_reads表示从物理磁盘中读取数据的请求次数，

所以innodb buffer的read命中率就可以这样得到：（Innodb_buffer_pool_read_requests - Innodb_buffer_pool_reads） / Innodb_buffer_pool_read_requests * 100%。

一般来讲这个命中率不会低于99%，如果低于这个值的话就要考虑加大innodb buffer pool，大家通常建议设置为系统内存的50%-80%