InnoDB waits for checkpoint.

The ratio of how often InnoDB needs to read or create a page where no clean pages are available. A good ratio value should stay below 1.

If innodb_buffer_pool_wait_free (wait_counter) is greater than 0, it is a strong indicator that the InnoDB buffer pool is too small, and operations had to wait on a checkpoint.

Data is retrieved from the performance_schema or information_schema database and the global_status table.