Simple Perl Progam To Save Server Load Every 30 Minutes To A File

i use the following perl script(created by me) to save server load every 30 minutes to a log file i just keep it running in the background(probably would be more effective using cron)

#!/usr/bin/perl

while(1) {
$w = `w`;
#print $w;
$w =~ /load average: (.+)
/;
$log = $1;
my ($sec, $min, $hour, $mday, $mon, $year) = localtime;
my $rightnow = sprintf("%04d-%02d-%02d %02d:%02d:%02d ", $year + 1900, $mon + 1, $mday, $hour, $min, $sec);
$log = $rightnow . ": " . $log ."
";
open (OUTFILE, ">>top_logfile.txt");
print OUTFILE "$log
";
close (OUTFILE);
#sleep for 30 minutes
sleep(1800);
}