Programmability issues

Programming models are at the very center of our effort to address the exascale challenge. They are the key interface that will allow the separation of the programmers' concerns from those of system designers, potentially at different levels of granularity. Any such model must meet the extensive needs of application developers and be supported by the entire software stack. Considerable research is needed to define and implement the programming and execution models for such systems. Whereas evolutionary approaches may best support the migration of existing application software, revolutionary models may be best suited to providing extreme-scale performance for new applications on emerging architectures. Both approaches should be explored.