We are hosting a VPS on a popular host and are experiencing a regular time drift of several minutes a day forward (approx 7).

Linux Kernel: 2.6.18-164.11.1.el5 GNU/Linux Distro: CentOS release 5.4 (Final)

We reached out to our hosting provider and their support advised us " This is a known issue with Cloud Servers. To fix this you will need to add one line to your grub config located at: /boot/grub/menu.lst

The line you need to add is: noapic nolapic divider=10 nolapic_timer

This should correct this issue. You will need to restart after this is added in. "

Because I am wary of manipulating grub, mostly I'm terrified that our server may fail to restart - I ask you guys, the pro *nix admins - where exactly in this file does the recommended insertion below:

# line from 1&1 for time syncing issue (Case 5163)
noapic nolapic divider=10 nolapic_timer

go? Please specify where exactly, and whether the order of commands is or is not important. Why is the block below "title CentOS ..." indented?

If someone could give me an overview of how this works or point me to a resource that's easy to follow, that's what I'm looking for immediately, a light overview or basic understanding of what I;m doing. If GRUB and bootloaders are a deep dark treasure trove of kernel hacking or something, that's great well-recommended in-depth resources are also very welcome.

This is my current /boot/grub/menu.lst

# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
#boot=/dev/sda
#
serial --unit=0 --speed=57600
terminal --timeout=5 serial console

timeout=5

title CentOS (2.6.18-164.11.1.el5)
    root (hd0,0)
    kernel /boot/vmlinuz-2.6.18-164.11.1.el5 ro root=/dev/hda1 console=tty0 console=tty
    initrd /boot/initrd-2.6.18-164.11.1.el5.img

MOST IMPORTANT: I need to know where in the file above it is appropriate to paste the suggested line so I can confidently restart my VPS after manipulating GRUB config