}else if(req->flags & RECV){//apply op on contiguous buffer for accumulate
int n =req->real_size/smpi_datatype_size(datatype);
smpi_op_apply(req->op, req->buf, req->old_buf, &n, &datatype);
}else if(req->flags & RECV){//apply op on contiguous buffer for accumulate
int n =req->real_size/smpi_datatype_size(datatype);
smpi_op_apply(req->op, req->buf, req->old_buf, &n, &datatype);