[Wien] WIEN2k and gfortran

[John Rundgren]

Dear Peter,
about the speed of gfortran+OpenBLAS and ifort+mkl:

In my previous message I used the 8-thread processors i7 and xeon, respectively. When the same test is repeated on the same xeon machine, computing time is 132 min and 138 min, respectively.

An amazing and hopeful result for poor researchers.

Most of the computing time is consumed in lapw0, lapw1, and lapw2. The following table shows the storage occupied by the corresponding binary files,

  binary   gfortran+OpenBLAS   ifort+mkl
  lapw0    568 kB              2.2 MB
  lapw1    344 kB              1.9 MB
  lapw2    490 kB              2.2 MB

The present test seems to indicate that the code refinement of ifort relative to gfortran is counterproductive for WIEN2k. But is the test result generally valid? More WIEN2k experience than mine is required for a response.

Best regards / John



________________________________
From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> on behalf of "Niedermayr, Arthur" <a.niedermayr at protonmail.com>
Sent: Wednesday, December 7, 2016 2:34 PM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] WIEN2k and gfortran

Hello Mr. Rundgren,

I wanted to ask you, why do I need the link /opt/OpenBLAS/include in linker flags?
And what about -lgfortran, -lpthread and "-I" option? What are they doing?


I am also using OpenBLAS with following options (without compilation errors):
L Linker Flags:         $(FOPT) -L../SRC_lib -L/opt/OpenBLAS/lib
R R_LIB (LAPACK+BLAS):  -llapack_lapw -lopenblas

Could I improve the calculation time of my program if I use your options?


Best regards
Arthur Niedermayr


Ps. I thought that the OpenBLAS library only replaces the BLAS library, but not the LAPACK library.




-------- Original Message --------
Subject: [Wien] WIEN2k and gfortran
Local Time: 5. Dezember 2016 11:54 AM
UTC Time: 5. Dezember 2016 10:54
From: jru at kth.se
To: wien at zeus.theochem.tuwien.ac.at <wien at zeus.theochem.tuwien.ac.at>



Dear WIEN2k team,

siteconfig and User's Guide can be updated concerning gfortran and BLAS:

 L Linker Flags:         $(FOPT) -I /opt/OpenBLAS/include -L/opt/OpenBLAS/lib
 R R_LIB (LAPACK+BLAS):  -lopenblas -lpthread -lgfortran

OpenBLAS being available from the sites

www.openblas.net and https://github.com/xianyi/OpenBLAS/wiki/Installation-Guide

In a test taking 2.5 h/iteration gfortran/ifort time was 1.3. A current test got interesting when one of my disks containing ifort crashed.

Regards,
John Rundgren




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