Linux – Does Linux kernel 3.x use the CFS process scheduler

You can find a general description of CFS here. It is not weight/cap based in the sense that it is not based on distributing an execution time quantum among the most fit processes. You might want to read about how nice levels are implemented also, which will make the distinction clear.

Is there some command i can use or a file i can check in order to find out which process scheduler im using on my linux system ?

No, because unlike WRT to the I/O scheduler, there is only one possibility: the CFS ("Completely Fair Scheduler"), which includes real-time capabilities. The CFS is named partly to distinguish it from the "O(1)" scheduler, which as noted in that article was superseded in version 2.6.23.

So if you have a kernel where you are not sure, just check the version number.