[petsc-dev] programming model for PETSc

[Matthew Knepley]

On Thu, Nov 24, 2011 at 4:09 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Jed,
>
>   Let's stop arguing about whether MPI is or is not a good base for the
> next generation of HPC software but instead start a new conversation on
> what API (implemented on top of or not on top of MPI/pthreads etc etc) we
> want to build PETSc on to scale PETSc up to millions of cores with large
> NUMA nodes and GPU like accelerators.
>
>    What do you want in the API?


Let's start with the "lowest" level, or at least the smallest. I think the
only sane way to program for portable performance here
is using CUDA-type vectorization. This SIMT style is explained well here
http://www.yosefk.com/blog/simd-simt-smt-parallelism-in-nvidia-gpus.html
I think this is much easier and more portable than the intrinsics for
Intel, and more performant and less error prone than threads.
I think you can show that it will accomplish anything we want to do. OpenCL
seems to have capitulated on this point. Do we agree
here?

   Matt


>
>   Barry
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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