setting dirty_ratio kernel parameter

Hello
I've a n issue in understanding the kernel parameter in title.
Red Hat Enterprise Linux Server release 6.6 kernel 2.6.32-504.8.1.el6.x86_64 running on a VMWare env.

grep dirty /etc/sysctl.conf
vm.dirty_background_ratio = 3
vm.dirty_ratio = 80
vm.dirty_expire_centisecs = 500
vm.dirty_writeback_centisecs = 100

sysctl -a |grep dirty
vm.dirty_background_ratio = 3
vm.dirty_background_bytes = 0
vm.dirty_ratio = 40
vm.dirty_bytes = 0
vm.dirty_writeback_centisecs = 100
vm.dirty_expire_centisecs = 500

cat /proc/sys/vm/dirty_ratio
40

This value is so just after reboot, so me question is the parameter in /etc/sysctl.conf must be the same of /proc/sys/vm/dirty_ratio or not?
On anoter server the above parameter are the same in both file and proc.

Thank you in advance
Kind Regards