Centre Blaise Pascal » HPL sur GPU

/* 

 * -- High Performance Computing Linpack Benchmark (HPL)                

 *    HPL - 2.0 - September 10, 2008                          

 *    Antoine P. Petitet                                                

 *    University of Tennessee, Knoxville                                

 *    Innovative Computing Laboratory                                 

 *    (C) Copyright 2000-2008 All Rights Reserved                       

 *                                                                      

 * -- Copyright notice and Licensing terms:                             

 *                                                                      

 * Redistribution  and  use in  source and binary forms, with or without

 * modification, are  permitted provided  that the following  conditions

 * are met:                                                             

 *                                                                      

 * 1. Redistributions  of  source  code  must retain the above copyright

 * notice, this list of conditions and the following disclaimer.        

 *                                                                      

 * 2. Redistributions in binary form must reproduce  the above copyright

 * notice, this list of conditions,  and the following disclaimer in the

 * documentation and/or other materials provided with the distribution. 

 *                                                                      

 * 3. All  advertising  materials  mentioning  features  or  use of this

 * software must display the following acknowledgement:                 

 * This  product  includes  software  developed  at  the  University  of

 * Tennessee, Knoxville, Innovative Computing Laboratory.             

 *                                                                      

 * 4. The name of the  University,  the name of the  Laboratory,  or the

 * names  of  its  contributors  may  not  be used to endorse or promote

 * products  derived   from   this  software  without  specific  written

 * permission.                                                          

 *                                                                      

 * -- Disclaimer:                                                       

 *                                                                      

 * THIS  SOFTWARE  IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,  INCLUDING,  BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY

 * OR  CONTRIBUTORS  BE  LIABLE FOR ANY  DIRECT,  INDIRECT,  INCIDENTAL,

 * SPECIAL,  EXEMPLARY,  OR  CONSEQUENTIAL DAMAGES  (INCLUDING,  BUT NOT

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 * THEORY OF LIABILITY, WHETHER IN CONTRACT,  STRICT LIABILITY,  OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 

 * ---------------------------------------------------------------------

 */ 

/*

 * Include files

 */

#include "hpl.h"

#ifdef STDC_HEADERS

void HPL_logsort

(

   const int                        NPROCS,

   const int                        ICURROC,

   int *                            IPLEN,

   int *                            IPMAP,

   int *                            IPMAPM1

)

#else

void HPL_logsort

( NPROCS, ICURROC, IPLEN, IPMAP, IPMAPM1 )

   const int                        NPROCS;

   const int                        ICURROC;

   int *                            IPLEN;

   int *                            IPMAP;

   int *                            IPMAPM1;

#endif

{

/* 

 * Purpose

 * =======

 *

 * HPL_logsort computes an array  IPMAP  and  its inverse  IPMAPM1  that

 * contain  the logarithmic sorted processes id with repect to the local

 * number of rows of  U  that they own. This is necessary to ensure that

 * the logarithmic spreading of U is optimal in terms of number of steps

 * and communication volume as well.  In other words,  the larget pieces

 * of U will be sent a minimal number of times.

 *

 * Arguments

 * =========

 *

 * NPROCS  (global input)                const int

 *         On entry, NPROCS  specifies the number of process rows in the

 *         process grid. NPROCS is at least one.

 *

 * ICURROC (global input)                const int

 *         On entry, ICURROC is the source process row.

 *

 * IPLEN   (global input/output)         int *

 *         On entry, IPLEN is an array of dimension NPROCS+1,  such that

 *         IPLEN[0] is 0, and IPLEN[i] contains the number of rows of U,

 *         that process i-1 has.  On exit,  IPLEN[i]  is  the number  of

 *         rows of U  in the processes before process IPMAP[i] after the

 *         sort,  with  the convention that  IPLEN[NPROCS] is  the total

 *         number  of rows  of the panel.  In other words,  IPLEN[i+1] -

 *         IPLEN[i] is  the  number of rows of A that should be moved to

 *         the process IPMAP[i].  IPLEN  is such that the number of rows

 *         of  the  source process  row is IPLEN[1] - IPLEN[0],  and the

 *         remaining  entries  of  this  array  are  sorted  so that the

 *         quantities IPLEN[i+1]-IPLEN[i] are logarithmically sorted.

 *

 * IPMAP   (global output)               int *

 *         On entry,  IPMAP  is an array of dimension  NPROCS.  On exit,

 *         array contains  the logarithmic mapping of the processes.  In

 *         other words, IPMAP[myroc] is the corresponding sorted process

 *         coordinate.

 *

 * IPMAPM1 (global output)               int *

 *         On entry, IPMAPM1  is an array of dimension NPROCS.  On exit,

 *         this  array  contains  the inverse of the logarithmic mapping

 *         contained  in  IPMAP:  IPMAPM1[ IPMAP[i] ] = i,  for all i in

 *         [0.. NPROCS)

 *

 * ---------------------------------------------------------------------

 */ 

/*

 * .. Local Variables ..

 */

   int                        dist, i, ip, iplen_i, iplen_j, itmp, j, k;

/* ..

 * .. Executable Statements ..

 */

/*

 * Compute the  logarithmic distance between process j and process 0, as

 * well as the maximum logarithmic distance. IPMAPM1 is workarray here.

 */

   for( j = 0, dist = 0; j < NPROCS; j++ )

   {

      IPMAP[j] = MModAdd( j, ICURROC, NPROCS ); ip = j; itmp = 0;

      do { if( ip & 1 ) itmp++; ip >>= 1; } while ( ip );

      IPMAPM1[j] = itmp; if( itmp > dist ) dist = itmp;

   }

/*

 * Shift IPLEN[1..NPROCS]  of ICURROC places,  so that  IPLEN[1]  is now

 * what used to be IPLEN[ICURROC+1]. Initialize IPMAP,  so that IPMAP[0]

 * is ICURROC.

 */

   for( j = 0; j < ICURROC; j++ )

   {

      for( i = 2, itmp = IPLEN[1]; i <= NPROCS; i++ ) IPLEN[i-1] = IPLEN[i];

      IPLEN[NPROCS] = itmp;

   }

/*

 * logarithmic sort

 */

   for( k = 1; k <= dist; k++ )

   {

      for( j = 1; j < NPROCS; j++ )

      {

         if( IPMAPM1[j] == k )

         {

            for( i = 2; i < NPROCS; i++ )

            {

               if( k < IPMAPM1[i] )

               {

                  iplen_i = IPLEN[i+1]; iplen_j = IPLEN[j+1];

                  if( iplen_j < iplen_i )

                  {

                     IPLEN[j+1] = iplen_i;  IPLEN[i+1] = iplen_j;

                     itmp       = IPMAP[j]; IPMAP[j]   = IPMAP[i];

                     IPMAP[i]   = itmp;

                  }

               }

            }

         }

      }

   }

/*

 * Compute IPLEN and IPMAPM1 (the inverse of IPMAP)

 */

   IPLEN[0] = 0;

   for( i = 0; i < NPROCS; i++ )

   {

      IPMAPM1[ IPMAP[i] ] = i;

      IPLEN[i+1]         += IPLEN[i];

   }

/*

 * End of HPL_logsort

 */

}