[gmx-developers] random123 library portability issues

[Roland Schulz]

HI Alexey ,


On Fri, May 30, 2014 at 6:52 AM, Alexey Shvetsov <alexxy at omrb.pnpi.spb.ru>
wrote:

> Hi!
>
> I tryed to build 5.0 branch on ARM board (dual core cortex-a7). It builds
> (if
> i define arm as allowed arch in features/gccfeatures.h) but some regression
> tests fails.
>

What compiler did you use? Which tests fail?

Roland


>
> В письме от 30 мая 2014 12:43:29 пользователь Szilárd Páll написал:
> > Hi,
> >
> > A few days ago I did some sanity checks by compiling and
> > regressiontesting the 5.0 branch on ARM. This exercise made me realize
> > that the recently included Random123 library is now the single most
> > limiting factor when it comes to portability. In fact, as it is not
> > optional, v5.0 is ATM practically limited to x86* and Powerpc64 (BGQ)
> > architectures -- based on the docs (see http://goo.gl/YdKofG)
> > Random123 has not been tested (let alone optimized) on anything else.
> > Additionally, note that the code won't even compile on non-supported
> > architectures, so in its current state GROMACS 5.0 won't compile on
> > anything else but x86* and PPC64, e.g. with gcc compilation will be
> > aborted by the "#error" in features/gccfeatures.h:38. Removing these
> > sanity checks does let the code compile on ARM and regressiontests do
> > pass, though.
> >
> > I've exchanged a couple of emails with the developers and they suggest
> > that in practice Threefry should work on ARM (and perhaps other
> > architectures too), but testing/validation is definitely necessary.
> > Performance is not optimized on unsupported architectures, I assume,
> > so some optimization may not hurt too - especially if there are cases
> > where we generate many PRNGs per step (BTW has the potential overhead
> > been assessed?).
> >
> > Cheers,
> > --
> > Szilárd
>
> --
> Best Regards,
> Alexey 'Alexxy' Shvetsov, PhD
> Department of Molecular and Radiation Biophysics
> FSBI Petersburg Nuclear Physics Institute, NRC Kurchatov Institute,
> Leningrad region, Gatchina, Russia
> mailto:alexxyum at gmail.com
> mailto:alexxy at omrb.pnpi.spb.ru
> --
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