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cuda

About

CUDA is a parallel computing platform and programming model that makes using a GPU for general purpose computing simple and elegant. The developer still programs in the familiar C, C++, Fortran, or an ever expanding list of supported languages, and incorporates extensions of these languages in the form of a few basic keywords.

Version and Availability

Softenv Keys for cuda on philip
Machine Version Softenv Key
philip 4.0.17 +cuda-4.0.17
philip 4.2.9 +cuda-4.2.9
▶ Display Softenv Keys for cuda all clusters
Machine Version Softenv Key
philip 4.0.17 +cuda-4.0.17
philip 4.2.9 +cuda-4.2.9
▶ Softenv FAQ?

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

Softenv

SoftEnv is a utility that is supposed to help users manage complex user environments with potentially conflicting application versions and libraries.

System Default Path

When a user logs in, the system /etc/profile or /etc/csh.cshrc (depending on login shell, and mirrored from csm:/cfmroot/etc/profile) calls /usr/local/packages/softenv-1.6.2/bin/use.softenv.sh to set up the default path via the SoftEnv database.

SoftEnv looks for a user's ~/.soft file and updates the variables and paths accordingly.

Viewing Available Packages

Using the softenv command, a user may view the list of available packages. Currently, it can not be ensured that the packages shown are actually available or working on the particular machine. Every attempt is made to present an identical environment on all of the LONI clusters, but sometimes this is not the case.

Example,

$ softenv
These are the macros available:
*   @default
These are the keywords explicitly available:
+amber-8                       Applications: 'Amber', version: 8 Amber is a
+apache-ant-1.6.5              Ant, Java based XML make system version: 1.6.
+charm-5.9                     Applications: 'Charm++', version: 5.9 Charm++
+default                       this is the default environment...nukes /etc/
+essl-4.2                      Libraries: 'ESSL', version: 4.2 ESSL is a sta
+gaussian-03                   Applications: 'Gaussian', version: 03 Gaussia
....
Listing of Available Packages

See Packages Available via SoftEnv on LSU HPC and LONI.

For a more accurate, up to date list, use the softenv command.

Caveats

Currently there are some caveats to using this tool.

  1. packages might be out of sync between what is listed and what is actually available
  2. resoft and soft utilities are not; to update the environment for now, log out and login after modifying the ~/.soft file.
Availability

softenv is available on all LSU HPC and LONI clusters to all users in both interactive login sessions (i.e., just logging into the machine) and the batch environment created by the PBS job scheduler on Linux clusters and by loadleveler on AIX clusters..

Packages Availability

This information can be viewed using the softenv command:

% softenv
Managing Environment with SoftEnv

The file ~/.soft in the user's home directory is where the different packages are managed. Add the +keyword into your .soft file. For instance, ff one wants to add the Amber Molecular Dynamics package into their environment, the end of the .soft file should look like this:

+amber-8

@default

To update the environment after modifying this file, one simply uses the resoft command:

% resoft

Usage

How you program for GPU process with CUDA depends on the language, choice of compilers, and toolset.

▶ Open Example?

Standard C:

void saxpy( int n, float a,
            float *x, float *y )
{
   for ( int i = 0; i < n; ++i )
      y[i] = a * x[i] + y[i];
}

int N = 1 << 20;

saxpy( N, 2.0, x, y );

C with CUDA Extensions:

__global__
void saxpy( int n, float a,
float *x, float *y )
{
   int i = blockIdx.x*blockDim.x + threadIdx.x;
   if ( i < n ) y[i] = a * x[i] + y[i];
}

int N = 1 << 20;
cudaMemcpy(x, d_x, N, cudaMemcpyHostToDevice);
cudaMemcpy(y, d_y, N, cudaMemcpyHostToDevice);

saxpy<<<4096,256>>>(N, 2.0, x, y);

cudaMemcpy(d_y, y, N, cudaMemcpyDeviceToHost);

Resources

Last modified: March 07 2013 12:30:04.