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From Marco de Abreu <marco.g.ab...@gmail.com>
Subject Re: [MXNET 2.0 Wishlist] [DISCUSS] Single build system
Date Fri, 05 Apr 2019 17:13:22 GMT
I think this is rather about the depreciation of the make based build
system. We currently have make and cmake in parallel but with diverging
feature support.

-Marco

Tianqi Chen <tqchen@cs.washington.edu> schrieb am Fr., 5. Apr. 2019, 11:42:

> I am in favor of using CMake. And I personally think CMake is not something
> that has to be introduced in a 2.0. It can simply be part of a minor
> release.
>
> Tianqi
>
> On Thu, Apr 4, 2019 at 10:31 AM Kellen Sunderland <kellen@apache.org>
> wrote:
>
> > Hello MXNet devs,
> >
> > I'd like to start a thread discussing what our build system should look
> > like in MXNet 2.0.  I'd propose that although the current make system has
> > served us well in the past, we remove it along with the bump to 2.0.  The
> > end goal I'd like to see is that we have a clean build system, without a
> > bunch of conditional logic that makes contributing and testing MXNet a
> > simpler process.  Additionally I'd propose we target a minimum cmake
> > version of 3.7 for reasons described below.
> >
> > First I'd like to give some context on why I'd propose we don't just
> switch
> > to cmake, but we also target a relatively new version (version 3.7 from
> > Nov, 2016) of cmake.  The largest benefits in making this change would
> > apply to CUDA builds where cmake itself has quite inconsistent
> > functionality between versions.  One persistent annoyance I've had with
> > cmake is that we've had conditional logic for the FindCUDA command which
> at
> > one point targeted some modern cmake features, but then in subsequent
> > versions of cmake the way these features works was tweaked, and now I
> find
> > these cmake features are consistently broken to the point that I require
> a
> > bunch of -D defines to compile properly or to use an IDE.  An additional
> > CUDA related issue is that every time there's a new SM added to NVCC we
> > have to make a few source changes to support it.  I could see this being
> > problematic for users who may suddenly realize that due to their
> > compilation settings, they may not actually be enabling the features they
> > think they are with their shiny new GPUs.
> >
> > As an alternative if we, for example, target cmake 3.7 at a minimum, and
> we
> > want to find cuda and then build a list of reasonable PTX/BINS we could
> use
> > the following command[1]:
> >
> > ----
> > FindCUDA(...)
> > ...
> > CUDA_SELECT_NVCC_ARCH_FLAGS(ARCH_FLAGS 3.0 3.5+PTX 5.2(5.0) Maxwell)
> >   LIST(APPEND CUDA_NVCC_FLAGS ${ARCH_FLAGS})
> > ----
> >
> > Simple, concise, and it would help to make the building experience more
> > consistent across platforms, build environments and IDEs (looking at you
> > CLion).  We'd of course need to do a little experimentation work to make
> > sure that this does indeed work as intended, and can replace the
> currently
> > complex findCuda logic we have in our build systems, but for the sake of
> > the proposal let's assume these cmake commands do indeed work
> consistently
> > as documented from cmake 3.7 onwards.
> >
> > To give users a chance to update their tooling I'd also suggest we begin
> > warning users at least a release in advance that make based builds will
> be
> > deprecated in MXNet 2.0 so they can begin migrating to cmake.  I'd also
> > want to display deprecation messages for unused cmake flags (such as the
> > profiler flag) for a release before the 2.0 release, and then remove them
> > in 2.0.
> >
> > Of course not all users have cmake 3.7 on their systems, some of our
> > employers force use to use ridiculously outdated linux distributions.
> The
> > good news for these users is that if we can offer Docker compilation with
> > an image that has a supported version of cmake and we should be able to
> > build a portable binary that work even with very old distributions of
> > Linux.  Additionally installing cmake from source is also fairly
> > straightforward [2] and works quite well on older distros in my
> experience.
> >
> > Looking forward to hearing what others think.  Any preferred build
> systems
> > that you all would want to use?  Is cmake the right system to centralize
> > on?  If so, is version 3.7 a reasonable minimum version to target?  Is
> the
> > 2.0 release a good point at which we can think about simplifying build
> > logic?
> >
> > 1: https://cmake.org/cmake/help/v3.7/module/FindCUDA.html
> > 2: https://github.com/Kitware/CMake
> >
>

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