Would it not be easier to say something to the effect of (*warning: untested code*):

#!/usr/bin/perl -w
use strict;

my $file = 'd:/temp/file.csv';
my %hash;

open(FILE, $file) or die("Can't open $file: $!\n");
while (<FILE>) {
  my ($src, $duh) = split /,/, $_, 2;
  $hash{$src}++;
}
close(FILE);

foreach my $ip (sort({$hash{$a} <=> $hash{$b}} keys %hash)) {
  print "$ip was seen $hash{$ip} times\n";
}
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The code assumes that you are only taking the first item out of each line, discarding the rest. When you do $hash{$src}++, it is created as a value of zero and incremented if it doesn't exist, or incremented if it does.

Hope that helps....