[CP2K:10266] Re: ELPA speed-up with Intel-compiled code

[Jerry Tanoury]

Nico, Juerg,

Thank you.  That all makes sense.

Best regards,
Jerry

On Friday, May 4, 2018 at 5:47:54 AM UTC-4, Nico Holmberg wrote:
>
> Hi Jerry,
>
> Just to expand on Juerg's answer, it appears that you are using the OT 
> method together with the FULL_SINGLE_INVERSE preconditioner 
> <https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/SCF/OT.html#list_PRECONDITIONER>. 
> ELPA won't accelerate such simulations because no direct diagonalization is 
> performed during the SCF run.
>
> If you swap the preconditioner to FULL_ALL, you should notice a ~50 % 
> improvement in the *first step* of each inner SCF loop iteration when you 
> use ELPA instead of ScaLAPACK. Futhermore, if you switch OT to a standard 
> diagonalization based SCF solver, each SCF iteration should be accelerated 
> by the same factor.  I would however recommend that you always use OT if 
> the system is suitable for the method.
>
>
> BR,
>
> Nico       
>
> torstai 3. toukokuuta 2018 19.24.34 UTC+3 jgh kirjoitti:
>>
>> Hi 
>>
>> how much time is used for Diagonalization in these runs? 
>> I would guess it is a rather small fraction. We developed the OT 
>> method especially to avoid diagonalization as much as possible. 
>> If this is in fact the case, no speedup can be expected by using 
>> ELPA. 
>>
>> best regards 
>>
>> Juerg 
>> -------------------------------------------------------------- 
>> Juerg Hutter                         Phone : ++41 44 635 4491 
>> Institut für Chemie C                FAX   : ++41 44 635 6838 
>> Universität Zürich                   E-mail: hut... at chem.uzh.ch 
>> Winterthurerstrasse 190 
>> CH-8057 Zürich, Switzerland 
>> --------------------------------------------------------------- 
>>
>> -----cp... at googlegroups.com wrote: ----- 
>> To: cp2k <cp... at googlegroups.com> 
>> From: Jerry Tanoury 
>> Sent by: cp... at googlegroups.com 
>> Date: 05/03/2018 06:15PM 
>> Subject: [CP2K:10266] Re: ELPA speed-up with Intel-compiled code 
>>
>> Dear Alfio, 
>> My apologies for not attaching these at the beginning.  The input and 
>> output files are now attached.  Please note that the file names (coordinate 
>> files, etc.) have been changed in the input and output files for 
>> proprietary reasons.  Also, the ELPA run was killed rather soon after it 
>> began because no speed-up was observed. 
>>
>> Best regards, 
>> Jerry 
>>
>> On Wednesday, May 2, 2018 at 2:57:12 PM UTC-4, Jerry Tanoury wrote: 
>> Dear forum, 
>> I am running CP2K version 5.1 compiled with Intel 2017 update 5 compilers 
>> and corresponding MKL libs.  The arch file is attached.  Everything runs as 
>> expected.  I then build ELPA-2016.05.004 as shown below and built an 
>> ELPA-enable cp2k version according to the attached arch file: 
>>
>>  ../configure 
>> --prefix=/cluster/home/tanoury/CP2K/intelbuilt_packages/2017u5/elpa-2016.05.004 
>> FC=mpiifort FCFLAGS=-O2 -xHost CC=mpiicc CFLAGS=-O2 -xHost 
>> --enable-option-checking=fatal --enable-static=yes --enable-avx2=no 
>> --enable-avx=no 
>> SCALAPACK_LDFLAGS=-L/cluster/home/tanoury/intel/2017u5/compilers_and_libraries_2017.5.239/linux/mkl/lib/intel64 
>> -lmkl_scalapack_lp64 -lmkl_intel_lp64 -lmkl_sequential -lmkl_core 
>> -lmkl_blacs_intelmpi_lp64 -lpthread 
>> -Wl,-rpath,/cluster/home/tanoury/intel/2017u5/compilers_and_libraries_2017.5.239/linux/mkl/lib/intel64 
>> SCALAPACK_FCFLAGS=-L/cluster/home/tanoury/intel/2017u5/compilers_and_libraries_2017.5.239/linux/mkl/lib/intel64 
>> -lmkl_scalapack_lp64 -lmkl_intel_lp64 -lmkl_sequential -lmkl_core 
>> -lmkl_blacs_intelmpi_lp64 -lpthread 
>> -I/cluster/home/tanoury/intel/2017u5/compilers_and_libraries_2017.5.239/linux/mkl/include/intel64/lp64 
>>
>>
>> When doing a speed test on 80 cores, I saw no speed-up from ELPA.  Is 
>> this unexpected?  Did I build ELPA correctly?  Perhaps I need to run on 
>> 100's of cores. 
>>
>> Thank you for the help, 
>> Jerry 
>>
>>   
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>>
>> [attachment "CP2K_Test.inp" removed by Jürg Hutter/at/UZH] 
>> [attachment "CP2K_Test1-ELPA.inp" removed by Jürg Hutter/at/UZH] 
>> [attachment "CP2K_Test1-ELPA.output" removed by Jürg Hutter/at/UZH] 
>>
>
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