On Tue, Nov 12, 2019 at 1:09 PM PIERRE AUGIER <
pierre.aug...@univ-grenoble-alpes.fr> wrote:

>
> > Date: Wed, 6 Nov 2019 23:49:08 -0500
> > From: Ralf Gommers <ralf.gomm...@gmail.com>
> > To: Discussion of Numerical Python <numpy-discussion@python.org>
> > Subject: Re: [Numpy-discussion] Transonic Vision: unifying
> >       Python-Numpy accelerators
> > Message-ID:
> >       <CABL7CQhr6ps25Yrp_pAF8vWVLS3_2=
> mw4bcoxb0h1dvu9aj...@mail.gmail.com>
> > Content-Type: text/plain; charset="utf-8"
> >
> > On Mon, Nov 4, 2019 at 4:54 PM PIERRE AUGIER <
> > pierre.aug...@univ-grenoble-alpes.fr> wrote:
> >
> >> Dear Python-Numpy community,
> >>
> >> Transonic is a pure Python package to easily accelerate modern
> >> Python-Numpy code with different accelerators (currently Cython, Pythran
> >> and Numba).
> >>
> >> I'm trying to get some funding for this project. The related work would
> >> benefit in particular to Cython, Numba, Pythran and Xtensor.
> >>
> >> To obtain this funding, we really need some feedback from some people
> >> knowing the subject of performance with Python-Numpy code.
> >>
> >> That's one of the reason why we wrote this long and serious text on
> >> Transonic Vision: http://tiny.cc/transonic-vision. We describe some
> >> issues (perf for numerical kernels, incompatible accelerators, community
> >> split between experts and simple users, ...) and possible improvements.
> >>
> >
> > Thanks Pierre, that's a very interesting vision paper.
>
> Thanks Ralf for this kind and interesting reply!
>
> >
> > In case you haven't seen it, there was a discussion on the pandas-dev
> > mailing list a couple of weeks ago about adopting Numba as a dependency
> > (and issues with that).
> >
> > Your comment on my assessment from 1.5 years ago being a little unfair to
> > Pythran may be true - not sure it was at the time, but Pythran seems to
> > mature nicely.
> >
> > The ability to switch between just-in-time and ahead-of-time compilation
> is
> > nice. One thing I noticed is that this actual switching is not completely
> > fluent: the jit and boost decorators have different signatures, and
> there's
> > no way to globally switch behavior (say with an env var, as for backend
> > selection).
>
> Yes, it seems evident now but I forgot to update the jit decorators when I
> was working on the boost decorator.
> My first "targets" for Transonic are packages for which the ahead-of-time
> mode seems more adapted.
>
> This incompatibility between the 2 main decorators used in Transonic will
> soon be fixed!
>
> Regarding the way to globally switch behavior, I'll open a dedicated issue.
>
> >> Help would be very much appreciated.
> >>
> >
> > I'd be interested to help think about adoption and/or funding.
> >
> > Cheers,
> > Ralf
> >
>
> As you've seen with the jit/boost incompatibility, I guess API design
> would be better if people knowing the subject could be included in some
> discussions.
>
> For example, I had to design the Python API for type declaration of arrays
> (see
> https://transonic.readthedocs.io/en/latest/generated/transonic.typing.html)
> since I didn't find anything adapted. My implementation is not great
> neither since types in transonic.typing and in `typing` are right now not
> compatible ! (However, it won't be difficult to fix that)
>
> Another API design that needs to be thought is about user-defined types in
> Transonic. This is for future because Pythran does not currently support
> that, but I think we will have to be able to support kind of dataclass,
> something like the equivalent of C struct (corresponding to Cython `cdef
> class` and Numba `jitclass`).
>
> A more theoretical subject that would be interesting to investigate is
> about the subset of Python-Numpy that can and should be implemented by
> accelerators.


This is indeed interesting, I've been thinking about this a lot and have a
very rough first cut at what should be included (
https://github.com/Quansight-Labs/rnumpy). That should be redone next year
with a better basis for decision-making of what should and should not be in
it.

For example, I think a function having different branches with different
> types for the returned objects depending of runtime values cannot be
> rewritten as efficient modern C++.
>

Agreed. That's anyway due to sub-optimal design decisions long ago in most
cases.

Cheers,
Ralf


> If you know people potentially interested to discuss about these subjects,
> please tell me.
>
> Cheers,
> Pierre
>
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