If you have modified your prefork or worker settings in your apache conf file you may also need to edit another file which is present in some CentOS Virtuozzo templates used by the system.
Operating System: CentOS
File Location: /etc/httpd/conf.d/
FileName: swtune.conf
Please make sure the prefork and worker settings in this file match your main apache configuration file and then reload apache or restart it if necessary
/etc/init.d/httpd reload
/etc/init.d/httpd restart
