simgrid::s4u::Exec::on_start_cb([](simgrid::s4u::Exec const& activity) {
if (activity.get_host_number() == 1) { // We only run on one host
simgrid::s4u::Host* host = activity.get_host();
simgrid::s4u::Exec::on_start_cb([](simgrid::s4u::Exec const& activity) {
if (activity.get_host_number() == 1) { // We only run on one host
simgrid::s4u::Host* host = activity.get_host();