use Time::HiRes qw( time );

$MDIR="/tmp/";
#save list into an array
open(LIST, "$MDIR/list"); @list=<LIST>; close LIST;

@updevices=grep(!/known down|unmanaged/i,@list);
my $start = Time::HiRes::gettimeofday();
foreach $element (@updevices)
{ 
        #hostname:status:ip
        @ip = split(':',$element);
        system("ping $ip[2] 1 &");
        $result = $?;
        print "ping $ip[0] $ip[2]  $result\n";
        if ( $result !=  0)
        {
                print "$ip[0] is dead\n";
        }

}
my $end = Time::HiRes::gettimeofday();
printf("%.2f\n", $end - $start);