How much real memory eated by all processes on the server

ps aux | awk '{print $2}' | grep -v 'PID' | xargs pmap -d | grep '^mapped' | awk '{print $4}' | sed 's/K//' | perl -e 'do { $a+=$_; $b++ } for <>;print $a/1024, « mb\n», $a/1024/$b, « mb\n»'