what's a reliable way to determine the ideal innodb_thread_concurrency setting?

on an article from 2006 , here they suggest such formula.

2*(number of cpus + Number of Disks)

has anyone tried their settings according to this formula ? or do you have any other formula ?

our server has 8 cores , no hyperthreading , and 1 disk. and we handle around 2-3 million requests everyday , around 40-50m sql queries.