MySQL innodb_read_io_threads setting with Linux native AIO

Hi,

Yes when an I/O request is completed (by  innodb_use_native_aio) and the I/O call returns, the InnoDB background thread that is handling the request calls an I/O completion routine and returns to process the next request. The number of requests that can be processed in parallel is n, where n is the number of InnoDB background threads. The number of InnoDB background threads is controlled by innodb_read_io_threads and innodb_write_io_threads.

You can configure the number of background threads that service read and write I/O on data pages using the innodb_read_io_threads and innodb_write_io_threads configuration parameters. These parameters signify the number of background threads used for read and write requests, respectively. They are effective on all supported platforms. You can set values for these parameters in the MySQL option file (my.cnf or my.ini); you cannot change values dynamically. The default value for these parameters is 4 and permissible values range from 1-64.

Cheers

This is what the MySQL documentation states.  But it does not mention how to determine if we are using too many background threads.  

Oracle support pointed to the following reference
Recommended Settings for MySQL 5.6, 5.7 Server for Online Transaction Processing (OLTP) and Benchmarking ( Doc ID 1531329.1 )
https://support.oracle.com/epmos/faces/DocumentDisplay?parent=SrDetailText&sourceId=3-17204500381&id=1531329.1