How to extend swap size in RHEL

[root@rhel_srv ~]# dd if=/dev/zero of=/swapfile bs=1024k count=16384
[root@rhel_srv ~]# mkswap /swapfile
Setting up swapspace version 1, size = 17179865 kB
[root@rhel_srv ~]# swapon /swapfile
[root@rhel_srv ~]# cat /proc/swaps
Filename Type Size Used Priority
/dev/mapper/vg.01-lv_swap partition 33554424 144 -1
/swapfile file 16777208 0 -2
Add to /etc/fstab
[root@rhel_srv ~]# vi /etc/fstab
/swapfile swap swap deafaults 0 0