parallel for_each not parallel?

[Germán Diago]

I tried to compile this code in parallel mode:

#include <parallel/algorithm>
#include <gtkmm.h>
#include <vector>
#include <tr1/functional>

void computeThumbnails(Glib::RefPtr<Gdk::Pixbuf> image, float ratio)
{
	image->scale_simple(image->get_width() * ratio,
						image->get_height() * ratio, Gdk::INTERP_BILINEAR);
	
}



int main(int argc, char * argv[])
{
	using namespace std::tr1;

	Gtk::Main m(argc, argv);
	Glib::Dir directory(argv[1]);
	

	std::vector<Glib::RefPtr<Gdk::Pixbuf> > v;

	std::string filename = directory.read_name();
	while (filename != "")
	{
		v.push_back(Gdk::Pixbuf::create_from_file(argv[1] + filename));
		filename = directory.read_name();
	}

	std::for_each(v.begin(), v.end(),
std::tr1::bind(&computeThumbnails,placeholders::_1, 0.3));
	return 0;	
}


With this command:

g++ `pkg-config gtkmm-2.4 --libs --cflags` -fopenmp -march=i686
-D_GLIBCXX_PARALLEL computafotos.cpp -o computafotos


with no luck. Am I doing anything wrong? Because I looked at the
system monitor and timed it and it's exactly the same as the
sequential version.