[QE-users] QE-7.1 and ELPA version

[Paolo Giannozzi]

On 4/17/23 09:47, Alireza Ghasemi wrote:

> I had set DFLAGS and autotools did not update it, therefore,
> "-D__ELPA" was missing during the compilation of LAXlib.

reminder to everybody: do not add any variable setting to "./configure" 
unless you are sure that you need it

> However, the performance of QE with ELPA is not better than QE with 
> scalapack. The system has more than 2,000 KS orbitals running on more 
> than 500 MPI processes.

elpa should scale better than scalapack, but not dramatically better.

> Also, I played around with "-nd" and "-nt" (the latter for FFT), they 
> have some significant impact on run time but the same for both ELPA and 
> scalapack.

-nt has no impact on subspace diagnalization / orthonormalization.
-nd sets the number of processors used by ELPA, so you should notice at 
least some difference

Paolo

> Do QE developers recommend users to use ELPA?
> 
> Is there a benchmark of QE comparing its performance with and without ELPA?
> 
> ***************
> 
> 
> On 4/15/23 10:08, Paolo Giannozzi wrote:
>> On 13/04/2023 19:28, Alireza Ghasemi wrote:
>>
>>>     Does anyone know the latest version of ELPA to which one can link 
>>> and build QE-7.1?
>>
>> from ./configure --help:
>>
>>   --with-elpa-version     Specify ELPA API version
>> (2015 for ELPA releases 2015.x and 2016.05;
>>  2016 for ELPA releases 2016.11, 2017.x and 2018.05;
>>  default 2018 for ELPA releases 2018.11 and beyond)
>>
>>> During configure of QE, I see the following warning:
>>>
>>> checking ELPA... configure: WARNING: *** Invalid ELPA version, 
>>> defaulting to 2018
>>>
>>> and then no "-D__ELPA" when compiling LAXlib Fortran files.
>>
>> this cannot happen. This is what happens:
>>
>>       if test "$with_elpa_version" = "2015"; then
>>         try_dflags="$try_dflags -D__ELPA_2015"
>>       elif test "$with_elpa_version" = "2016"; then
>>         try_dflags="$try_dflags -D__ELPA_2016"
>>       elif test "$with_elpa_version" = "2017"; then
>>         try_dflags="$try_dflags -D__ELPA_2016"
>>       elif test "$with_elpa_version" = "2018"; then
>>         try_dflags="$try_dflags -D__ELPA"
>>       else
>>         AC_MSG_WARN([*** Invalid ELPA version, defaulting to 2018])
>>         try_dflags="$try_dflags -D__ELPA"
>>       fi
>>
>> Paolo
>>
>>>
>>>
>>> Best regards
>>>
>>> Alireza
>>>
>>>
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> -- 
> Dr. S. Alireza Ghasemi
> Training & Support
> Erlangen National High Performance Computing Center
> Friedrich-Alexander-Universität Erlangen-Nürnberg
> Martensstrasse 1, 91058 Erlangen, Germany
> https://hpc.fau.de/about-us/people
> 

-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222