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:                                                             

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

 *                                                                      

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

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 *                                                                      

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 * 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.                                                          

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 * -- Disclaimer:                                                       

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 * THIS  SOFTWARE  IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

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

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

 */ 

/*

 * Include files

 */

#include "hpl.h"

#ifdef STDC_HEADERS

void HPL_pdfact

(

   HPL_T_panel *                    PANEL

)

#else

void HPL_pdfact

( PANEL )

   HPL_T_panel *                    PANEL;

#endif

{

/* 

 * Purpose

 * =======

 *

 * HPL_pdfact recursively factorizes a  1-dimensional  panel of columns.

 * The  RPFACT  function pointer specifies the recursive algorithm to be

 * used, either Crout, Left- or Right looking.  NBMIN allows to vary the

 * recursive stopping criterium in terms of the number of columns in the

 * panel, and  NDIV  allow to specify the number of subpanels each panel

 * should be divided into. Usuallly a value of 2 will be chosen. Finally

 * PFACT is a function pointer specifying the non-recursive algorithm to

 * to be used on at most NBMIN columns. One can also choose here between

 * Crout, Left- or Right looking.  Empirical tests seem to indicate that

 * values of 4 or 8 for NBMIN give the best results.

 *  

 * Bi-directional  exchange  is  used  to  perform  the  swap::broadcast

 * operations  at once  for one column in the panel.  This  results in a

 * lower number of slightly larger  messages than usual.  On P processes

 * and assuming bi-directional links,  the running time of this function

 * can be approximated by (when N is equal to N0):                      

 *  

 *    N0 * log_2( P ) * ( lat + ( 2*N0 + 4 ) / bdwth ) +

 *    N0^2 * ( M - N0/3 ) * gam2-3

 *  

 * where M is the local number of rows of  the panel, lat and bdwth  are

 * the latency and bandwidth of the network for  double  precision  real

 * words, and  gam2-3  is  an estimate of the  Level 2 and Level 3  BLAS

 * rate of execution. The  recursive  algorithm  allows indeed to almost

 * achieve  Level 3 BLAS  performance  in the panel factorization.  On a

 * large  number of modern machines,  this  operation is however latency

 * bound,  meaning  that its cost can  be estimated  by only the latency

 * portion N0 * log_2(P) * lat.  Mono-directional links will double this

 * communication cost.

 *

 * Arguments

 * =========

 *

 * PANEL   (local input/output)          HPL_T_panel *

 *         On entry,  PANEL  points to the data structure containing the

 *         panel information.

 *

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

 */ 

/*

 * .. Local Variables ..

 */

   void                       * vptr = NULL;

   int                        align, jb;

/* ..

 * .. Executable Statements ..

 */

   jb = PANEL->jb; PANEL->n -= jb; PANEL->ja += jb;

   if( ( PANEL->grid->mycol != PANEL->pcol ) || ( jb <= 0 ) ) return;

#ifdef HPL_DETAILED_TIMING

   HPL_ptimer( HPL_TIMING_RPFACT );

#endif

   align = PANEL->algo->align;

   vptr  = (void *)malloc( ( (size_t)(align) + 

              (size_t)(((4+((unsigned int)(jb) << 1)) << 1) )) *

              sizeof(double) );

   if( vptr == NULL )

   { HPL_pabort( __LINE__, "HPL_pdfact", "Memory allocation failed" ); }

/*

 * Factor the panel - Update the panel pointers

 */

   PANEL->algo->rffun( PANEL, PANEL->mp, jb, 0, (double *)HPL_PTR( vptr,

                       ((size_t)(align) * sizeof(double) ) ) );

   if( vptr ) free( vptr );

   PANEL->A   = Mptr( PANEL->A, 0, jb, PANEL->lda );

   PANEL->nq -= jb; PANEL->jj += jb;

#ifdef HPL_DETAILED_TIMING

   HPL_ptimer( HPL_TIMING_RPFACT );

#endif

/*

 * End of HPL_pdfact

 */

}