High Performance Computing

The information here is applicable to LSU HPC and LONI systems.

Shells

A user may choose between using /bin/bash and /bin/tcsh. Details about each shell follows.

/bin/bash

System resource file: /etc/profile

When one access the shell, the following user files are read in if they exist (in order):

1. ~/.bash_profile (anything sent to STDOUT or STDERR will cause things like rsync to break)
2. ~/.bashrc (interactive login only)
3. ~/.profile

When a user logs out of an interactive session, the file ~/.bash_logout is executed if it exists.

The default value of the environmental variable, PATH, is set automatically using SoftEnv. See below for more information.

/bin/tcsh

The file ~/.cshrc is used to customize the user's environment if his login shell is /bin/tcsh.

Modules

Modules is a utility which helps users manage the complex business of setting up their shell environment in the face of potentially conflicting application versions and libraries.

Default Setup

When a user logs in, the system looks for a file named .modules in their home directory. This file contains module commands to set up the initial shell environment.

Viewing Available Modules

The command

$ module avail

displays a list of all the modules available. The list will look something like:

--- some stuff deleted ---
velvet/1.2.10/INTEL-14.0.2
vmatch/2.2.2

---------------- /usr/local/packages/Modules/modulefiles/admin -----------------
EasyBuild/1.11.1       GCC/4.9.0              INTEL-140-MPICH/3.1.1
EasyBuild/1.13.0       INTEL/14.0.2           INTEL-140-MVAPICH2/2.0
--- some stuff deleted ---

The module names take the form appname/version/compiler, providing the application name, the version, and information about how it was compiled (if needed).

Managing Modules

Besides avail, there are other basic module commands to use for manipulating the environment. These include:

add/load mod1 mod2 ... modn . . . Add modules
rm/unload mod1 mod2 ... modn  . . Remove modules
switch/swap mod . . . . . . . . . Switch or swap one module for another
display/show  . . . . . . . . . . List modules loaded in the environment
avail . . . . . . . . . . . . . . List available module names
whatis mod1 mod2 ... modn . . . . Describe listed modules

The -h option to module will list all available commands.

Module is currently available only on SuperMIC.

Fortran Source

!**********************************************
! THIS EXAMPLE USES THE LAPACK ROUTINE DGESV 
! TO SOLVE A SYSTEM OF LINEAR EQUATIONS AX=B 
! A = [1, 2, 3; 4, 5, 6; 7, 8 10]            
! B = [1, 0; 0, 1; 0, 0]
! *********************************************
 program lapack_test
  integer ipiv(3), info, i, j
  double precision A(3,3), B(3,2)
  A(1,1)=1
  A(1,2)=2
  A(1,3)=3
  A(2,1)=4
  A(2,2)=5
  A(2,3)=6
  A(3,1)=7
  A(3,2)=8
  A(3,3)=10
  
  B(1,1)=1
  B(2,1)=0
  B(3,1)=0
  B(1,2)=0
  B(2,2)=1
  B(3,2)=0

  call dgesv (3,2,A,3,ipiv,B,3,info)
  if(info .EQ. 0) then
     do i=1,3
        write(*,'(2F8.3)') (B(i,j), j=1,2)
     enddo
  endif
 end program lapack_test

Build and Execute

$ ifort lapack_test.f90 -llapack
$ ./a.out
  -0.667  -1.333
  -0.667   3.667
   1.000  -2.000

C Source

$ cat lapack_test.c
/**********************************************
 * THIS EXAMPLE USES THE LAPACK ROUTINE DGESV 
 * TO SOLVE A SYSTEM OF LINEAR EQUATIONS AX=B 
 * A = [1, 2, 3; 4, 5, 6; 7, 8 10]            
 * B = [1, 0; 0, 1; 0, 0]
 **********************************************/
#include 

extern void dgesv_(int*, int*, double*, int*, int*, double*, int*, int*);

int main()
{
  int n, nrhs, lda, ldb, IPIV[3], info, i;
  double A[3][3], B[2][3];  // Matrices must be transposed
  A[0][0] = 1; A[1][0] = 2; A[2][0] = 3;
  A[0][1] = 4; A[1][1] = 5; A[2][1] = 6;
  A[0][2] = 7; A[1][2] = 8; A[2][2] = 10;

  B[0][0] = 1; B[0][1] = 0; B[0][2] = 0;
  B[1][0] = 0; B[1][1] = 1; B[1][2] = 0;

  n = 3;
  nrhs = 2;
  lda = 3;
  ldb = 3;
  
  dgesv_(&n, &nrhs, (double *)A, &lda, IPIV, (double *)B, &ldb, &info);

  if(info == 0)
    {
      for(i = 0; i < 3; i++)
	printf("%8.3f %8.3f\n", B[0][i], B[1][i]);
    }
}

Build and Execute

C Source

$ cat lapack_test.c
/**********************************************
 * THIS EXAMPLE USES THE LAPACK ROUTINE DGESV 
 * TO SOLVE A SYSTEM OF LINEAR EQUATIONS AX=B 
 * A = [1, 2, 3; 4, 5, 6; 7, 8 10]            
 * B = [1, 0; 0, 1; 0, 0]
 **********************************************/
#include 

extern void dgesv_(int*, int*, double*, int*, int*, double*, int*, int*);

int main()
{
  int n, nrhs, lda, ldb, IPIV[3], info, i;
  double A[3][3], B[2][3];  // Matrices must be transposed
  A[0][0] = 1; A[1][0] = 2; A[2][0] = 3;
  A[0][1] = 4; A[1][1] = 5; A[2][1] = 6;
  A[0][2] = 7; A[1][2] = 8; A[2][2] = 10;

  B[0][0] = 1; B[0][1] = 0; B[0][2] = 0;
  B[1][0] = 0; B[1][1] = 1; B[1][2] = 0;

  n = 3;
  nrhs = 2;
  lda = 3;
  ldb = 3;
  
  dgesv_(&n, &nrhs, (double *)A, &lda, IPIV, (double *)B, &ldb, &info);

  if(info == 0)
    {
      for(i = 0; i < 3; i++)
	printf("%8.3f %8.3f\n", B[0][i], B[1][i]);
    }
}

Build and Execute