How to synchronize update and render functions in 2d games

This may seems pretty basic, but I'm really wondering what's the best way to make sure a game has the time to update all its logic before rendering?

If we take the NES for example, if you know the cost of each instructions you can calculate how much time your logic takes before the VBlank so you are using most of the processing time available. Nowadays, it's pretty much impossible to do that kind of thing with modern computers.

I just want to know what I can use to scale my game and to be able to keep track of the cost of the functionalities I'm implementing so I can assure a solid framerate.