I am doing a project in linux kernel programming in which i want to checkpoint a process which is running at different interval of time and restoring it when needed please if any one has any idea about how to go about in this project please help me in doing my project.

Well, we don't want to tell you how to do it, but you know, Linux does this sort of thing on a grand scale when it "suspends" .. as when a laptop user closes the lid. That should give you some good code to study.

can any one tell me how to add a new file iin the system files that is the kernel code and compile it

That might be a bit high-tech for here. But most such things are handled using kernel modules.

Also... "checkpoint / restart" is often something that an application does for itself, perhaps in response to a signal. The application saves its own state into some file, and knows how to restore that state later.

This approach has the advantage of being a "designed-in" characteristic of the application itself. The application, upon receiving the order to checkpoint, brings itself to a good stopping-place, then saves the checkpoint information. Should it then need to restart from that checkpoint, it once again brings itself to that same "good stopping-place," then restores (and validates!) the checkpoint image. It does this with the one advantage that the kernel does not have: the application knows very intimately what it is doing and why. The kernel doesn't. The kernel must view "every application" as basically a generic thing.