Difference between revisions of "Main Page/hybrid prog"

From Nekcem
Jump to navigationJump to search
Line 1: Line 1:
 
This is the document page for hybrid programming proposal for [http://www.mcs.anl.gov/~mmin/nekcem.html NekCEM] (some notes taken from DOE Exascale workshop).
 
This is the document page for hybrid programming proposal for [http://www.mcs.anl.gov/~mmin/nekcem.html NekCEM] (some notes taken from DOE Exascale workshop).
  
==Approaches ==
+
==Programming Model Approaches ==
 
* hybrid/evolutionary: MPI+ ___ ?
 
* hybrid/evolutionary: MPI+ ___ ?
 
** MPI for inter-node prog, since # notes and inter-node concerns not expected to change dramatically
 
** MPI for inter-node prog, since # notes and inter-node concerns not expected to change dramatically

Revision as of 12:18, 31 January 2011

This is the document page for hybrid programming proposal for NekCEM (some notes taken from DOE Exascale workshop).

Programming Model Approaches

  • hybrid/evolutionary: MPI+ ___ ?
    • MPI for inter-node prog, since # notes and inter-node concerns not expected to change dramatically
      • support for hybrid programming/interoperability
      • purer one-sided communications; active messages
      • asynchronous collectives
    • something else for intra-node
      1. OpenMP
        • introduction of locality-oriented concepts?
        • efforts in OpenMP 3.0 ?
      2. PGAS languages
        • already support a notation of locality in a shared namespace
        • UPC/CAF need to relax strictly SPMD execution model
      3. Sequoia
        • support a strong notation of vertical locality


  • unified/holistic: __ ?
    • a single notation for inter- and intra-node programming?
    • traditional PGAS languages: UPC, CAF, Titanium
      • require extension to handle nested parallelism, vertical locality
    • HPCS languages: Chapel, X10, Fortress(?)
      • designed with locality and post-SPMD parallelism in mind
    • other candidates: Charm++, Global Arrays, Parallel X, ...
  • others
    • mainstream multi-core/GPU language: (sufficient promise to be funded?)
    • domain-specific language
      • fit your problem?
      • should focus on more general solutions
    • functional languages
      • never heavily adopted in mainstream or HPC
      • copy-on-write optimization and alias analysis?
    • parallel scripting languages?


Expectation

  • parallelism: nested, dynamic, loosely-coupled, data-driven (i.e. post-SPMD programming/execution models)
    • to take advantage of architecture
    • to better support load balancing and resilience
  • locality: concepts for vertical control as well as horizontal (i.e. locality within a node rather than simply between nodes)

Tools: Debuggers, perf. analysis

  • challenges
    • need aggregation to hide details
    • need to report info in user's terms
  • good area for innovation (e.g. execution visualization to understand mapping of code to hardware)