I've never liked shouting up the stairs, my mam used to really annoy me at different times of the day screaming my name up the stairs and expecting me to drop what I was doing, and come running down, only to find she wanted to tell me something absolutely trivial.
So I always go upstairs and tell my son I'm dishing up tea and it will be on the table in 3 minutes. He has normally been down twice while it was cooking and was told the same time it would be ready twice. Then we sit down to eat tea and he is nowhere to be seen. My wife refuses to start hers and thinks I'm mean by tucking into mine while it is still hot. Screw that, if he can not drag his arse away from his PC to eat his tea at the same time as everyone else, that is his business. We eat around the same time every day and he has been told 3 times, just minutes ago. His problem.