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DEGAS

From Modelado Foundation

Revision as of 22:55, February 5, 2013 by imported>Cdenny
DEGAS
File:Your-team-logo.png
Team Members LBNL, Rice U., UC Berkeley, UT Austin, LLNL, NCSU
PI Katherine Yelick (LBNL))
Co-PIs Vivek Sarkar (Rice U.), James Demmel (UC Berkeley),

Mattan Erez (UT Austin), Dan Quinlan (LLNL)

Website team website
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Team Members

  • Lawrence Berkeley National Laboratory (LBNL)
  • Rice University
  • University of California, Berkeley
  • University of Texas at Austin
  • Lawrence Livermore National Laboratory (LLNL)
  • North Carolina State University (NCSU)


Mission

Mission Statement: To ensure the broad success of Exascale systems through a unified programming model that is productive, scalable, portable, and interoperable, and meets the unique Exascale demands of energy efficiency and resilience.

Goals & Objectives

  • Scalability: Billion‐way concurrency, thousand‐way on chip with new architectures
  • Programmability: Convenient programming through a global address space and high‐level abstractions for parallelism, data movement and resilience
  • Performance Portability: Ensure applications can be moved across diverse machines using implicit (automatic) compiler optimizations and runtime adaptation
  • Resilience: Integrated language support for capturing state and recovering from faults
  • Energy Efficiency: Avoid communication, which will dominate energy costs, and adapt to performance heterogeneity due to system-­‐level energy management
  • Interoperability: Encourage use of languages and features through incremental adoption

Roadmap

Any Roadmap to be included?


Impact

Any Impact to be included?


Programming Models

Two Distinct Parallel Programming Questions

  • What is the parallel control model?

Example.jpg

  • What is the model for sharing/communication?

Example.jpg

=== Applications Drive New Programming Models

  • Message Passing Programming
    • Divide up domain in pieces
    • Compute one piece and exchange
    • MPI and many libraries
  • Global Address Space Programming
    • Each start computing
    • Grab whatever/whenever
    • UPC, CAF, X10, Chapel, Fortress, Titanium, GlobalArrays

Hierarchical Programming Model

  • Goal: Programmability of exascale applications while providing scalability, locality, energy efficiency, resilience, and portability
    • Implicit constructs: parallel multidimensional loops, global distributed data structures, adaptation for performance heterogeneity
    • Explicit constructs: asynchronous tasks, phaser synchronization, locality
  • Built on scalability, performance, and asynchrony of PGAS models
    • Language experience from UPC, Habanero‐C, Co‐Array Fortran, Titanium
  • Both intra and inter‐node; focus is on node model
  • Languages demonstrate DEGAS programming model
    • Habanero‐UPC: Habanero’s intra‐node model with UPC’s inter‐node model
    • Hierarchical Co‐Array Fortran (CAF): CAF for on‐chip scaling and more
    • Exploration of high level languages: E.g., Python extended with H‐PGAS
  • Language‐independent H‐PGAS Features:
    • Hierarchical distributed arrays, asynchronous tasks, and compiler specialization for hybrid (task/loop) parallelism and heterogeneity
    • Semantic guarantees for deadlock avoidance, determinism, etc.
    • Asynchronous collectives, function shipping, and hierarchical places
    • End‐to‐end support for asynchrony (messaging, tasking, bandwidth utilization through concurrency)
    • Early concept exploration for applications and benchmarks

Communication-Avoiding Compilers

Software Stack