Optimizing Mysql: thread_concurrency

While optimizing our mysql server here at work I tried modifying the value of thread_concurrency with very little effect the servers performance. Further research (aka googling) shows that this value actually only works with Solaris, we're using Fedora Core. It's even on the manual, I wonder why they never even bothered to add that to the comment for this variable.

# Try number of CPU's*2 for thread_concurrency

thread_concurrency = 2

From the manual

This variable is specific to Solaris systems, for which mysqld invokes the thr_setconcurrency() with the variable value. This function enables applications to give the threads system a hint about the desired number of threads that should be run at the same time. This variable was added in MySQL 3.23.7.

http://dev.mysql.com/doc/refman/4.1/en/server-system-variables.html#sysvar_thread_concurrency

http://dev.mysql.com/doc/refman/5.1/en/server-system-variables.html#sysvar_thread_concurrency