title: innodb_read_io_threads missing on MySQL 5.1.69
body: <p>I have a production 64-bit MySQL DB server (version 5.1.69 - Source distribution) with 8 cores and 8 GB RAM, and I want it to fully utilize all cores and all available memory. I use InnoDB and I read that I should set the following in <code>my.cnf</code> configuration file:</p>
  
  <pre><code>innodb_read_io_threads          = 64
  innodb_write_io_threads         = 64
  </code></pre>
  
  <p>From some reason, both variables don't exist. When I add them to the configuration file, MySQL fails to load. Moreover, the following query returns zero results:</p>
  
  <pre><code>show global variables like '%innodb_read_%';
  </code></pre>
  
  <p>Any suggestions? Thanks.</p>