my $before = current_memory();
my $after = current_memory();

SomethingSomething();

print join "\n",
'    Before  ', format_memory($before),
'    After   ', format_memory($after),
'    Diff    ', format_memory($after - $before),
    ''
    ;


sub format_memory {
    my ($self, $memory) = @_;
    1 while $memory =~ s/^([-+]?\d+)(\d{3})/$1,$2/;
    return "$memory KB";
}

sub current_memory {
    my $self = shift;
    my $out  = `ps -o rss= -p $$`;
    $out =~ s/^\s*|\s*$//gs;
    $out;
}