Hello Apan --

Are you referring to the ‘mData’ chunking in 
modules/internal/DefaultRectangular.chpl?  If so, that has to do with the 
so-called ‘multi-ddata’ feature, which split the underlying storage for default 
rectangular arrays into multiple pieces (chunks) instead of just one piece.  
The intent was that for NUMA architectures those pieces could be separately 
placed on different NUMA nodes and we would be able to achieve perfect NUMA 
storage/execution affinity despite the fact that locality is page-based.  
Unfortunately this work turned out to introduce other overheads that we 
couldn’t get rid of, so it’s been disabled for general use (via the param 
defRectDisableMultiDData).  You can ignore it.

greg


> On Jun 29, 2017, at 11:12 AM, Qasem, Apan M <[email protected]> wrote:
> 
> Hello, 
> 
> I am implementing data layout transformations in Chapel that favor the 
> GPU/heterogenous memory hierarchy. 
> 
> I have been studying the dists and layout codes in the Chapel distribution.  
> I was wondering if someone can help me understand (or point me to 
> documentation that explains) the idea behind “chunking” in data layouts.  It 
> appears that it is only used when the array element is a compound (mdata) 
> type. But I can’t figure out what it is meant to do by reading the code. 
> 
> Thanks. 
> 
> - Apan
> 
> Apan Qasem, PhD
> Visiting Scholar, AMD Research
> Associate Professor, Dept of Computer Science  
> Texas State University
> http://www.cs.txstate.edu/~aq10
> 
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