use Devel::Size qw(size total_size);
sub foo {
    print "in foo\n";
}
print "size foo: ",size(*foo),"\n";
print "total_size foo: ",total_size(*foo),"\n";
print "size bar: ",size(*bar),"\n";
print "total_size bar: ",total_size(*bar),"\n";
print "difference: ",size(*foo) - size(*bar),"\n";
__END__
size foo: 7034
total_size foo: 7034
size bar: 7186
total_size bar: 7186
difference: -152