====== 5. Seminar - Parallel programming for SMS (C language + OpenMP) ======

Task to practice on seminar: EN: {{ .:05_seminar_assignment-en.pdf |}} CZ: {{.:05_cviceni_zadani.pdf|}}\\
Prepared basic program for image sharpening (template code for seminar project 4): 
  * win {{courses:B4M35PAP:tutorials:05:program_ostreni_obrazu.zip|}} 
  * linux {{:courses:B4M35PAP:tutorials:05:program_ostreni_obrazu_linux.zip|}}

OpenMP specification and documentation
  * http://www.openmp.org/
  * https://computing.llnl.gov/tutorials/openMP/
  * http://pages.tacc.utexas.edu/~eijkhout/pcse/html/
Complete lectures of Tim Mattson’s (Intel)
  * http://www.openmp.org/wp-content/uploads/Intro_To_OpenMP_Mattson.pdf
  * http://tinyurl.com/OpenMP-Tutorial (kompletní kurz na Youtube)

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Measure the execution time of part of a program under Windows using //QueryPerformanceCounter//() from //windows.h// library:
<code C>
  LARGE_INTEGER start, stop, frequency;
  long overhead;
  QueryPerformanceFrequency(&frequency);
  QueryPerformanceCounter(&start);
  QueryPerformanceCounter(&stop);
  overhead = stop.QuadPart-start.QuadPart;
  
  //------------------------------
  QueryPerformanceCounter(&start);
  // ...
  QueryPerformanceCounter(&stop);
  //------------------------------

  cout << " Execution time of observed program portion is "
       << 1000*(stop.QuadPart - start.QuadPart - overhead)/(double)frequency.QuadPart
       << " ms" << endl;
</code>
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Execution time of part of a program under Linux with use of //clock_gettime//() from //time.h// header file.
<code C>

    struct timespec start, stop;
    double elapsed;
    
    //------------------------------
    clock_gettime(CLOCK_REALTIME, &start);
    // ...
    clock_gettime(CLOCK_REALTIME, &stop);
    //------------------------------

    elapsed = ( stop.tv_sec - start.tv_sec )*1000
             + (double)( stop.tv_nsec - start.tv_nsec )/(double)1000000;
    printf( " Execution time of observed program portion is %lf ms\n", elapsed);
</code>
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-------
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Files for installation (to work on tasks at home):

  - Cygwin (C/C++ a OpenMP) http://www.cygwin.com/
  - MPICH 2, Win IA32  (library MPI) http://www.mcs.anl.gov/research/projects/mpich2/
  - NetBeans IDE with C/C++ language support http://netbeans.org/downloads/index.html

Remark NetBeans installation is not mandatory. Programs can be edited even in Notepad (http://notepad-plus-plus.org).
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It is necessary to mark for in Cygwin installation next packages/components from development section:
    *  binutils
    *  gcc core
    *  gcc g++
    *  gcc mingw core
    *  gcc mingw g++
    *  gdb
    *  libboost
    *  make
    *  mingw runtime

Install also all automatically selected components.
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If you decide to use NetBeans:
<note>
It is necessary to add path to Cygwin binaries to executables search path %PATH%. It can be done by next command in command line: setx path "%path%;C:\Cygwin \\ 

MPI executables directory neds to be added to search path as well: setx path "%path%;C:\Program Files (x86)\MPICH2\bin

Option setup in NetBeans IDE: \\ 
Tools -> Options -> C/C++ -> karta "Build Tools" -> Tool Collection -> Add.. -> Cygwin \\
Tools -> Options -> C/C++ -> karta "Code Assistance" -> Tool Collection -> Cygwin \\
and insert MPICH2 in Include directories list: C:\Program Files (x86)\MPICH2\include


On the "Build Tools" tab in the same dialog (Tools -> Options -> C/C++) next setup should be seen:
  * Base Director: C:\Cygwin\bin
  * C compiler C:\Cygwin\bin\gcc.exe
  * C++ Compiler: C:\Cygwin\bin\g++-3.exe
  * Assembler: C:\cygwin\bin\as.exe
  * Make Command: C:\Cygwin\bin\make.exe
  * Debugger: C:\Cygwin\bin\gdb.exe
</note>

NetBeans setup for correct compilation of developed programs:
<note>
**OpenMP**:  \\ 
File -> Project Properties:

  C Compiler:
    - Additional Options: -fopenmp

 \\ 
-----------------------------------------------------------------------------------
 \\ 
**MPI**:  \\ 
File -> Project Properties:

  C Compiler:
    - Include directories: .../Program Files/MPICH2/include
  Linker:
    - Additional Library directories: .../Program Files/MPICH2/lib
    - Libraries: mpi.lib


 \\ 
-----------------------------------------------------------------------------------
 \\ 
**OpenMP & MPI**:  \\ 
File -> Project Properties:

  C Compiler:
    - Include directories: .../Program Files/MPICH2/include
    - Additional Options: -fopenmp
  Linker:
    - Additional Library directories: .../Program Files/MPICH2/lib
    - Libraries: mpi.lib
</note>


The program.c compilation from Cygwin command line "Cygwin Bash Shell" (without NetBeans use) with g++ (gcc, mpiCC):
<note>
**OpenMP**:  \\ 
  g++ program.c -fopenmp

 \\ 
-----------------------------------------------------------------------------------
 \\ 
**MPI**:  \\ 
  g++ program.c -I"C:\Program Files\MPICH2\include" -L"C:\Program Files\MPICH2\lib"  -lmpi


 \\ 
-----------------------------------------------------------------------------------
 \\ 
**OpenMP & MPI**:  \\ 
  g++ program.c -fopenmp -I"C:\Program Files\MPICH2\include" -L"C:\Program Files\MPICH2\lib"  -lmpi
</note>

Example program for development environment testing - program.c:
<note>
**OpenMP**:
<code C>
#include <stdio.h>
#include <omp.h>

int main(int argc, char *argv[]) {
  int iam = 0, np = 1;

 #pragma omp parallel default(shared) private(iam, np)
  {
    np = omp_get_num_threads();
    iam = omp_get_thread_num();
    printf("Hello from thread %d out of %d \n", iam, np);
  }
  
  return 0;
}
</code>
 \\ 
-----------------------------------------------------------------------------------
 \\ 
**MPI**:
<code C>
#include <stdio.h>
#include "mpi.h"
 
int main(int argc, char *argv[]) {
  int numprocs, rank, namelen;
  char processor_name[MPI_MAX_PROCESSOR_NAME];
 
  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Get_processor_name(processor_name, &namelen);
 
  printf("Hello from process %d out of %d on %s\n",
          rank, numprocs, processor_name);
 
  MPI_Finalize();
  return 0;
}
</code>
 \\ 
-----------------------------------------------------------------------------------
 \\ 
**OpenMP & MPI**:
<code C>
#include <stdio.h>
#include "mpi.h"
#include <omp.h>

int main(int argc, char *argv[]) {
  int numprocs, rank, namelen;
  char processor_name[MPI_MAX_PROCESSOR_NAME];
  int iam = 0, np = 1;

  MPI_Init(&argc, &argv);
  MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Get_processor_name(processor_name, &namelen);

 #pragma omp parallel default(shared) private(iam, np)
  {
    np = omp_get_num_threads();
    iam = omp_get_thread_num();
    printf("Hello from thread %d out of %d from process %d out of %d on %s\n",
           iam, np, rank, numprocs, processor_name);
  }

  MPI_Finalize();
  return 0;
}
</code>
</note>
Remark: Do not forget to copy or locate required libraries in directory with compiled and started program (usual file names: cyggcc_s-1.dll, cyggomp-1.dll, cygstdc++-6.dll, cygwin1.dll).