[CP2K:2310] Re: CP2K build with Intel Compiler and MKL

Ondrej Marsalek ondrej.... at gmail.com
Sun Oct 4 09:22:42 CEST 2009


All I can say to this, based on my own experience and talking to other
users, is that the situation is very disappointing and discouraging,
no matter what the causes are.

I have made a parallel build with gfortran 4.3.3 and Intel MKL that is
able to run all the tests. I made the arch file from the gfortran
serial version and library settings for my older Intel build. I attach
it in case someone is interested.

Ondrej


On Sat, Sep 26, 2009 at 20:02, Axel Kohlmeyer <akoh... at gmail.com> wrote:
>
>>
>> This sounds quite scary to me. CP2K is notoriously tricky to compile
>> and so far for me the only reasonable way to tell whether I have a
>> working binary was to see if it can run the regtests successfully.
>> What you are saying means that this is not a very good method.
>
> well, you have to compare with other codes, where there is not such
> a detailed library of tests at all, but people just run a few test
> systems and when they work well, they are happy. on top of that you
> have the fact, that some people are better at writing "stable" code
> than others and that some problems only show up in cases that were
> not considered when writing the original code, or due to bad
> interactions
> with some higher or lower level code that got changed. the flexibility
> that makes cp2k a unique computational tool is at the same time its
> biggest enemy, as it causes a complexity that is hard to control,
> particularly in an environment with multiple developers, where not
> everybody has the same attitude to software development.
>
> that all being said, i don't know of any better alternative.
> the failing regtest example that you mentioned is using a
> feature, that the people i am supporting don't use, so at
> the moment, it doesn't bother me much, that this regtest would
> fail. the features, that we are using, seem to be working stable
> and have not created much problems for a long time. the majority
> of the problematic regtests seem to be related to not so commonly
> used features.
>
>> I do realize that I can never be sure that the build is 100% good.
>> However, in this case, I can't even tell if the build is wrong. It
>> crashes on the tests, but perhaps it is due to unstable tests,
>> perhapas it is due to miscompilation. This is really nasty.
>>
>> Let me ask a slightly more general question. Does anyone routinely run
>> a build that does not pass the tests? Does it work well outside of the
>> tests?
>
> i am seeing _much_ less problems when using g95 and juerg recently
> mentioned that his group would be mainly using gfortran 4.4.x.
> i have not yet tested a newer gfortran, but my measure of checking
> whether there is a real bug in the code is whether i can reproduce
> this issue with the g95 build, and for production runs, i usually
> run the exact system with a g95 and intel build side-by-side for a
> bit and see if the results are equivalent.
>
> [...]
>
>> I do all of this on the x86-64 platform. Also, it certainly is not
>> only the Intel compiler that has (or did have) trouble producing a
>> build that would pass the tests.
>
> indeed, you cannot imagine the pains that i had to go through to get
> a working executable on a cray xt3, where there was only a limited
> collection
> of PGI fortran compilers available, all of them badly broken wrt.
> cp2k.
> the only way to get a reasonable executable would be to build all
> object
> files with g95 using a special flag to not use the fortran startup
> code,
> write a c-wrapper for that and then link with the (PGI compiled) MPI,
> scalapack, blacs, blas, etc. libraries.
>
> there is some hope though, since cray has now bought the pathscale
> compiler division, but then again, it is hard to imagine that as
> small a shop as cray is, that they will have the manpower to follow
> the complexity of the new fortran language features with the level
> of detail that cp2k requires, as most current codes are much less
> demanding.
>
> cheers,
>    axel.
>
>> Ondrej
> >
>
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