This is right! What ouput do you get when you restart the service?
If your goal was to mark ICMP traffic with "EF," it is working. However, I would use this only for testing purposes and not prioritize all ICMP traffic.
Start by only prioritizing your game traffic. See here:
Watch is an application that makes it easier to see if marked packets really are hitting your queues. This command uses:
tc -s qdisc
every 2 seconds and only shows the relevant lines of the realtime class (1:11)
Then everything should be working