Changes between Version 14 and Version 15 of Status/May11


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Timestamp:
Apr 28, 2011 12:29:50 PM (3 years ago)
Author:
chak
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  • Status/May11

    v14 v15  
    7474== Data Parallel Haskell == 
    7575 
    76 '''Manuel: Any status update? Previous entry below''' 
     76The main user-visible development concerning data-parallel programming with GHC since the last status report is the release of our library for regular, multi-dimensional, shape-polymorphic arrays: [[http://hackage.haskell.org/package/repa Repa]].  The current release on Hackage performs well with GHC 7.0.3 and already includes Ben's recent work on high-performance stencil-based convolutions — see also the draft paper [http://www.cse.unsw.edu.au/~benl/papers/stencil/stencil-icfp2011-sub.pdf Stencil] and Ben's screencast [[http://code.ouroborus.net/beholder/video/Edge480.mov EdgeDetect]] of a real-time edge detection application, written in Objective-C and Haskell, using the new Repa library. 
    7777 
    78   ''Since the last report, we have continued to improve support for nested parallel divide-and-conquer algorithms.  We started with [[http://darcs.haskell.org/packages/dph/dph-examples/spectral/QuickHull/dph/QuickHullVect.hs QuickHull]] and are now working on an implementation of the [[http://darcs.haskell.org/packages/dph/dph-examples/real/BarnesHut/Solver/NestedBH/Solver.hs Barnes-Hut]] ''n''-body algorithm.  The latter is not only significantly more complex, but also requires the vectorisation of recursive tree data-structures, going well beyond the capabilities of conventional parallel-array languages.  In time for the stable branch of GHC 7.0, we replaced the old, per-core sequential array infrastructure (which was part of the sub-package `dph-prim-seq`) by  the [[http://hackage.haskell.org/package/vector vector package]] — vector started its life as a next-generation spin off of `dph-prim-seq`, but now enjoys significant popularity independent of DPH.'' 
    79  
    80   ''The new handling of INLINE pragmas as well as other changes to the Simplifier improved the stability of DPH optimisations (and in particular, array stream fusion) substantially.  However, the current candidate for GHC 7.0.1 still contains some performance regressions that affect the DPH and [[http://hackage.haskell.org/package/repa Repa]] libraries and to avoid holding up the 7.0.1 release, we decided to push fixing these regressions to GHC 7.0.2.  More precisely, we are planning a release of DPH and Repa that is suitable for use with GHC 7.0 for the end of the year, to coincide with the release of GHC 7.0.2.  From GHC 7.0 onwards, the library component of DPH will be shipped separately from GHC itself and will be available to download and install from Hackage as for other libraries.'' 
    81  
    82   ''To catch DPH performance regressions more quickly in the future, Ben Lippmeier implemented a performance regression testsuite that we run nightly on the HEAD.  The results can be enjoyed on the GHC developer mailing list.'' 
    83  
    84   ''Sadly, Roman Leshchinskiy has given up his full-time engagement with DPH to advance the use of Haskell in the financial industry.  We are looking forward to collaborating remotely with him.'' 
     78We have pushed back the release of a stable version of the main DPH libraries again.  They are now scheduled to be released with the forthcoming GHC 7.2. 
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    108102 
    109103 * [Hoopl] Hoopl: A Modular, Reusable Library for Dataflow Analysis and Transformation, http://research.microsoft.com/en-us/um/people/simonpj/papers/c--/dfopt.pdf  
     104 
     105 * [Stencil] Efficient Parallel Stencil Convolution in Haskell, Lippmeier et al., http://www.cse.unsw.edu.au/~benl/papers/stencil/stencil-icfp2011-sub.pdf 
     106 
     107 * [!EdgeDetect] http://code.ouroborus.net/beholder/video/Edge480.mov