[Haskell-cafe] repa parallelization results

Carter Schonwald carter.schonwald at gmail.com
Sat Mar 14 16:21:43 UTC 2015


dense matrix product is not an algorithm that makes sense in repa's
execution model,
in square matrix multiply of two N x N matrices, each result entry depends
on 2n values total across the  two input matrices.
even then, thats actually the wrong way to parallelize dense matrix
product! its worth reading the papers about goto blas and the more recent
blis project. a high performance dense matrix multipy winds up needing to
do some nested array parallelism with mutable updates to have efficient
sharing of sub computations!



On Fri, Mar 13, 2015 at 9:03 PM, Anatoly Yakovenko <aeyakovenko at gmail.com>
wrote:

> you think the backed would make any difference?  this seems like a
> runtime issue to me, how are the threads scheduled by the ghc runtime?
>
> On Fri, Mar 13, 2015 at 4:58 PM, KC <kc1956 at gmail.com> wrote:
> > How is the LLVM?
> >
> > --
> > --
> >
> > Sent from an expensive device which will be obsolete in a few months! :D
> >
> > Casey
> >
> >
> > On Mar 13, 2015 10:24 AM, "Anatoly Yakovenko" <aeyakovenko at gmail.com>
> wrote:
> >>
> >> https://gist.github.com/aeyakovenko/bf558697a0b3f377f9e8
> >>
> >>
> >> so i am seeing basically results with N4 that are as good as using
> >> sequential computation on my macbook for the matrix multiply
> >> algorithm.  any idea why?
> >>
> >> Thanks,
> >> Anatoly
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