How to know if your fps is good?

So I was just playing Chivalry, and my 7950 usually does a great job of handling that game. However, on 1 map in particular and on servers with 64 people, my fps becomes unplaying and I have to drop the settings from max to medium/medium high. Is this normal, is it just the massive amounts of people. What framerates should I expect from a 7950 when maxed out?

You shouldn't have any problems playing this game at its maxed settings. The problem maybe with the way the players are networking with each other. 

so the fps drops are caused by the server? should i just try joining a different 64 player server and try testing that out?

Play servers with a low "ping". It could be the server you were playing on. The 7950 is a great card. Especially when it is overclocked

Also, you can download fraps (or other software), if you haven't already. That will add an FPS counter on your screen. It is beneficial if you want some indiciation of how well your 7950 performs across different games.