dt_size_send = smpi_datatype_size(sendtype);
extra->send_size = sendcount*dt_size_send;
extra->datatype2 = encode_datatype(recvtype, &known);
dt_size_send = smpi_datatype_size(sendtype);
extra->send_size = sendcount*dt_size_send;
extra->datatype2 = encode_datatype(recvtype, &known);