[gmx-users] Intel MKL taken in preference of the specified FFT library

[Reuti]

Hi Mark,

thy for your reply and clarification about the library issue.

> Am 16.07.2015 um 20:43 schrieb Mark Abraham <mark.j.abraham at gmail.com>:
> 
> Hi,
> 
> On Thu, Jul 16, 2015 at 5:47 PM Reuti <reuti at staff.uni-marburg.de> wrote:
> 
>> Hi,
>> 
>> I just downloaded Gromacs 5.1-rc1 and want to compile it using the GNU
>> compilers and a self compiled FFTW*. I configured Gromacs with:
>> 
>> $ cmake .. -DCMAKE_INSTALL_PREFIX=/home/reuti/local/gromacs-5.1-rc1
>> -DGMX_FFT_LIBRARY=fftw3 -DCMAKE_PREFIX_PATH=/home/reuti/local/fftw-3.3.4
>> 
>> As there was now shared version of FFTW it complains about it, and hence I
>> compiled FFTW again - this time with shared library flag and the configure
>> step of Gromacs succeeded. But after `make` and `make install` I faced the
>> result, that the binary `gmx` like the library in "lib64" were linked
>> against Intel MKL. Well, there is an old version of the Intel MKL on the
>> system and hence in the LD_LIBRARY_PATH. Once I cleared the LD_LIBRARY_PATH
>> I got the result I expected.
>> 
> 
> Older MKL had a "feature" of providing headers that look like FFTW but
> execute MKL, and programs will find that if it precedes real FFTW in the
> lookup path.
> 
> 
>> Question: is this the intended behavior? IMO the GMX_FFT_LIBRARY=fftw3
>> flag should be honored first and any set LD_LIBRARY_PATH ignored.
>> 
> 
> Yes, but Intel decided to be "compatible" a.k.a. "deceptive." IIRC enough
> people complained that it got fixed for subsequent MKL. Meanwhile, our
> CMake code is quite complicated enough without double-checking for every
> possible rare case ;-) Meanwhile, there are ways of forcing the find
> mechanism to find the FFTW you really want.
> 
> 
>> 
>> -- Reuti
>> 
>> *) The automatic download (like outlined in the INSTALL:
>> -DGMX_BUILD_OWN_FFTW=ON -DREGRESSIONTEST_DOWNLOAD=ON) of FFTW and the
>> regression tests points to the Gromacs site, but AFAICS they were moved to
>> box.com, hence the automatic download fails.
>> 
> 
> No, the FFTW download goes to its site, and the tests download goes to
> gerrit.gromacs.org. None of that has changed.

For the FFTW you are right, I overlooked that it was complaining about the regression test only:

*********************
CMake Error at tests/CMakeLists.txt:57 (message):
  error: downloading
  'http://gerrit.gromacs.org/download/regressiontests-5.1-rc1.tar.gz' failed

  status_code: 1

  status_string: "Unsupported protocol"

  log: Hostname was NOT found in DNS cache

    Trying 130.237.25.133...

  Connected to gerrit.gromacs.org (130.237.25.133) port 80 (#0)

  GET /download/regressiontests-5.1-rc1.tar.gz HTTP/1.1

  User-Agent: curl/7.38.0

  Host: gerrit.gromacs.org

  Accept: */*

  

  HTTP/1.1 302 Found

  Date: Fri, 17 Jul 2015 10:08:02 GMT

  Server Apache/2.2.22 (Ubuntu) is not blacklisted

  Server: Apache/2.2.22 (Ubuntu)

  Location:
  https://kth.box.com/shared/static/xq0o95adj3076allx3feugtw4qrjlk9f.gz
*********************

Without the protocol error it would have downloaded from the final destination without getting noticed. But " HTTP/1.1 302 Found" is an URL redirect.

-- Reuti


> 
> Mark
> 
> 
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