"reserve shared memory (errno = 22)" typical mean you trying to access more huge pages you have reserved or the application don't have access to them.
Remember to give the user access to call the memlock system calls in /etc/security/limits.conf
I found this guide very useful when enable huge pages http://andrigoss.blogspot.dk/2008/02/jvm-performance-tuning.html
Do you really need a permGen of 6 GB?
Thanks for the response.
Actually, we do need a large Heap and Perm Size as the application server should be able to support more than 5k users and some applications use a large amount of memory.
Once we resume Performance Testing the applications on JBoss, we will make the configuration changes and get back to you incase of any warning / errors.