getting started on MKL - Error in opening the compiled module file.

[Ben_T_1]

I've freshly installed the Intel® Parallel Studio XE Composer Edition for Fortran OS X* (student version). It comes with the Math Kernel Library, which is why I bought it. I'm having a hard time getting started with MKL though. Here's what I've done step-by-step. (sorry for the beginner question, this is probably really obvious to everyone else here). 

1) Installed Intel® Parallel Studio XE Composer Edition for Fortran OS X* (no problem). I can run a 'hello world' script using ifort and throw the -mkl link command on at the end with no problem (not calling any mkl commands just yet).

2) Following these instructions I set my environment variables using a script provided by intel (located in opt/intel/bin to be precise). I have the intel 64-bit architecture (according to ifort -V) so I navigate to opt/intel/mkl/bin and run bash mklvars.sh intel64 mod ilp64. It runs without error (or any output, I assume it's working).

3) I write the following code to use MKL's gemm command for fortran95. Just multiplying 2 matrices. 

program test

implicit none
real, dimension(2,2) :: testA, testB, testC

testA = 1
testB = 1
testC = 0  ! I don't think I need this line, but it shouldn't matter

call gemm(testA, testB, testC)

write(*,*) testC

end program test

4) I compile with ifort test_mkl.f90 -o test -mkl. I get the following error:

Undefined symbols for architecture x86_64:
  "_gemm_", referenced from:
      _MAIN__ in ifortSTVOrB.o
ld: symbol(s) not found for architecture x86_64

5) I try ifort test_mkl.f90 -o test -L/opt/intel/mkl/lib -mkl and get the same result.

6) If I add the line USE mkl95_blas, ONLY: gemm,  above implicit none in both of the above examples I get:

    test_mkl.f90(4): error #7002: Error in opening the compiled module file. Check INCLUDE paths. [MKL95_BLAS] 
    USE mkl95_blas, ONLY: gemm
--------^
test_mkl.f90(12): error #6406: Conflicting attributes or multiple declaration of name.   [GEMM]
    call gemm(testA, testB, testC )
---------^
test_mkl.f90(4): error #6580: Name in only-list does not exist.   [GEMM]
    USE mkl95_blas, ONLY: gemm
--------------------------^
compilation aborted for test_mkl.f90 (code 1)

If your curious, I have successfully run this example script in XCODE using MKL, so it's definitely something I'm doing and not my installation. Specifically, my .mod files are built and are in the directories in the Include statement below (generate the same error as above). 
 

ifort test_mkl.f90  -I/opt/intel/mkl/include/intel64/ilp64 -L/opt/intel/mkl/lib/  -mkl -lmkl_blas95
ifort test_mkl.f90  -I/opt/intel/composer_xe_2015.3.187/mkl/include/intel64/ilp64 -L/opt/intel/composer_xe_2015.3.187/mkl/lib/
ifort test_mkl.f90  -I/opt/intel/composer_xe_2015.3.187/mkl/inlcude/intel64/ilp64 -L/opt/intel/composer_xe_2015.3.187/mkl/lib/  -mkl -lmkl_blas95

[mecej4 · Accepted solution]

You are a bit lax in using Blas/Lapack routines through Fortran 95 interfaces. When you use Blas95/Lapack95 routines such as gemm(), you must provide an interface. Failing to do so will give linker errors, at least.

Secondly, the name of the module that supplies the interface should match the name of the module included in your specific version of MKL. Look at the names in the mkl/include/intel64/ilp64 directory or in the table "Interface Libraries and Modules" in the MKL user guide. I think that the file name is blas95.mod (I don't have OSX, so check this), so you should say USE BLAS95.

[Ben_T_1]

Thanks mecej4,

Changing the USE statement allowed me to compile. I then ran into the problem from this thread and had to run the terminal command: 
source /opt/intel/composer_xe_2015.3.187/mkl/bin/mklvars.sh intel64

It works, but I'm curious if that 'source' command took care of the interface issues you mentioned? 

[Ying_H_Intel]

Hi Ben, Mecej4,

Thanks for raising and answer the problems. It seems the Fortran 95 interface bring a lot of trouble here.

For beginner, I recommend you to build and run the example code under MKL install folder.  /opt/intel

For example, under Linux (similar as Mac OS), 

>cp /opt/intel/composer_xe_2015.2.164/mkl/examples/examples_f95.tgz  .

>tar -xzvf examples_f95.tgz

GEMM sample code is:

> vi blas95/source/dgemmx.f90

  program   DGEMM_MAIN
      use f95_precision, only: wp => dp
      use blas95, only: gemm

      implicit none

1. if you'd like try Fotran Blas 95 interface,  the blod is needed.   please also check the name as mecej4 mentioned.  It should be same name as the *.mod file 

[yhu5@prc-mic01 lp64]$ ls
blas95.mod  f95_precision.mod  lapack95.mod  mkl_service.mod
[yhu5@prc-mic01 lp64]$ pwd
/opt/intel/composer_xe_2015.2.164/mkl/include/intel64/lp64

2. build and run the sample.

2.1 source compiler, which include ifort and mkl environment setting.

[yhu5@prc-mic01 lp64]$ source /opt/intel/composer_xe_2015.2.164/bin/compilervars.sh intel64
[yhu5@prc-mic01 lp64]$ ifort -V
Intel(R) Fortran Intel(R) 64 Compiler XE for applications running on Intel(R) 64, Version 15.0.2.164 Build 20150121
Copyright (C) 1985-2015 Intel Corporation.  All rights reserved.

2.2 build the sample

[yhu5@prc-mic01 blas95]$ make sointel64 function=dgemmx
make dgemmx.res  EXT=so _IA=intel64 RES_EXT=so
make[1]: Entering directory `/home/yhu5/mkl_example/blas95'
mkdir -p ./_results/intel_lp64_parallel_intel_iomp5_intel64_so

 ifort   -I /opt/intel/composer_xe_2015.2.164/mkl/include/intel64/lp64 -w source/dgemmx.f90 source/common_func.f /opt/intel/composer_xe_2015.2.164/mkl/lib/intel64/libmkl_blas95_lp64.a  -L"/opt/intel/composer_xe_2015.2.164/mkl/lib/intel64" -lmkl_intel_lp64 -lmkl_intel_thread -lmkl_core -L"/opt/intel/composer_xe_2015.2.164/mkl/../compiler/lib/intel64" -liomp5 -lpthread -ldl  -o _results/intel_lp64_parallel_intel_iomp5_intel64_so/dgemmx.out
 

Notes: please make sure

1. you have libmkl_blas95_lp64.a installed.

2. ifort  -mkl  =   -L"/opt/intel/composer_xe_2015.2.164/mkl/lib/intel64" -lmkl_intel_lp64 -lmkl_intel_thread -lmkl_core -L"/opt/intel/composer_xe_2015.2.164/mkl/../compiler/lib/intel64" -liomp5 -lpthread -ldl 

So Ben's command line should ok

ifort test_mkl.f90  -I/opt/intel/composer_xe_2015.3.187/mkl/inlcude/intel64/ilp64 -L/opt/intel/composer_xe_2015.3.187/mkl/lib/  -mkl -lmkl_blas95 (if libmkl_blas95.a is there).

3. regarding the functionality of  source compilervars.sh intel64 before run the program or build the program.

It will set MKLROOT, MKL  Include, library path, and run-time path etc. so you can  build and run the code easily.  Otherwise you need manually  write all path in command line and also need to set  below  (if dynamic link. -mkl is dynamic link by default). at run time.

export LD_LIBRARY_PATH (DYLD_LIBRARY_PATH)="/opt/intel/composer_xe_2015.2.164/mkl/lib/intel64":"/opt/intel/impi/4.1.2.040/intel64/lib:/opt/intel/composer_xe_2015.2.164/compiler/lib/intel64:/opt/intel/mic/coi/host-linux-release/lib:/opt/intel/mic/myo/lib:/opt/intel/composer_xe_2015.2.164/mpirt/lib/intel64:/opt/intel/composer_xe_2015.2.164/ipp/../compiler/lib/intel64

4. About ILP64 and LP64,  32bit or Intel 64.  You may read the MKL user guide for more details.

https://software.intel.com/en-us/articles/intel-math-kernel-library-documentation

Best Regards,

Ying