use RRDp;
 RRDp::start "/usr/local/bin/rrdtool";
 RRDp::cmd   qw(create demo.rrd --step 100 
               DS:in:GAUGE:100:U:U
               RRA:AVERAGE:0.5:1:10);
 $answer = RRDp::read;
 print $$answer;
 ($usertime,$systemtime,$realtime) =  ($RRDp::user,$RRDp::sys,$RRDp::real);