在innodb儲存中大量使用了AIO（Async IO）來處理些IO請求，這樣可以極大提高資料庫效能。而IO Thread 的主要工作是要負責這些IO請求的回撥（call back）處理。innodb1.0版本之前共有4個IO Thread，分別是write，read，insert buffer，log IO thread。在Linux平臺下，IO Thread的數量可以根據CPU核數來更改相應的引數值了，預設是4。，但是在Windows品臺下可以通過 innodb_read_io_threads 和 innodb_write_io_threads 兩個引數進行設定。

假如CPU是2顆8核的，那麼可以設定：
innodb_read_io_threads = 8
innodb_write_io_threads = 8

如果資料庫的讀操作比寫操作多，那麼可以設定：
innodb_read_io_threads = 10
innodb_write_io_threads = 6

也就是說，你可以根據情況加以設定。

注意

這兩個引數不支援動態改變，需要把該引數加入my.cnf裡，修改完後重啟MySQL服務，允許值的範圍是1～64。

調整完成後，你可以用命令“show engine innodb status\G;”來檢視調整結果，如下所示：
show engine innodb status
--------
FILE I/O
--------
I/O thread 0 state: waiting for completed aio requests (insert buffer thread)
I/O thread 1 state: waiting for completed aio requests (log thread)
I/O thread 2 state: waiting for completed aio requests (read thread)
I/O thread 3 state: waiting for completed aio requests (read thread)
I/O thread 4 state: waiting for completed aio requests (read thread)
I/O thread 5 state: waiting for completed aio requests (read thread)
I/O thread 6 state: waiting for completed aio requests (write thread)
I/O thread 7 state: waiting for completed aio requests (write thread)
I/O thread 8 state: waiting for completed aio requests (write thread)
I/O thread 9 state: waiting for completed aio requests (write thread)