[MPICH] MPICH105 shm drops packages on SUN niagara

[chong tan]

In the 'change liost' of the new 106 release, I see thie item:
   
  
Bugfix for shm and ssm channels. Added missing read and write memory barriers for x86, and missing volatile in packet structure    
  does it means this problem is fixed ?
   
  thanks
  

William Gropp <gropp at mcs.anl.gov> wrote:
  We're looking at it; I've added a variation of this to our regular tests.  No solution yet, however.  My guess is that there is a missing volatile or memory barrier somewhere; this should force us to clean up the current code.  

  Bill
  
    On May 16, 2007, at 12:18 PM, chong tan wrote:

      No taker on this ?  There is an identical proble on Linux.  Just that I am not sure if this code can reproduce the problem. 
  tan
  

 
  ----- Original Message ----
From: chong tan <chong_guan_tan at yahoo.com>
To: mpich-discuss at mcs.anl.gov
Sent: Friday, April 27, 2007 3:24:09 PM
Subject: Re: [MPICH] MPICH105 shm drops packages on SUN niagara

    The following code reproduces the problem.  I think you maybe able to reproduce the error on
  Linux, but I am not sure.
   
   
  It is best to run :
  mpiexec -n 8 a.out
  to reproduce the problem.  You will need a machine with 8CPU/cores.  SOmetime you will need to
  run the code multiple time to see the error.
   
  there will be files fast_mpi_?.dmp created, where ? is the rank of the related 'rank'.  When MPI get stuck,
  you should look at the last line of fast_mpi_0.dmp.  If it says:
  
  read from child 7

   
  then you should look at the last line of fast_mpi_7.dmp, it will say:
    read from master

   
  hope this help to debug the error.
   
  thanks
  tan
  
---------------------
  #include "stdlib.h"
#include "stdio.h"
#include "mpi.h"
   
  #define LOOP_COUNT  1000000
#define DATA_SIZE   4
#define MP_TAG      999
  main()
{
    int     nProc, rank ;
    int     argc = 0 ;
    int     i, j, status ;
    char    buf[ 128 ] ;
    FILE    *pf ;
      MPI_Init( &argc, NULL ) ;
    MPI_Comm_size( MPI_COMM_WORLD, &nProc ) ;
    MPI_Comm_rank( MPI_COMM_WORLD, &rank ) ;
    sprintf( buf, "fast_mpi_%d.dmp", rank ) ;
    pf = fopen( buf, "w" ) ;
      if( !rank ) {
       int      **psend ;
       int      **precv ;
         psend = (int**)calloc( nProc, sizeof( int *) ) ;
       precv = (int**)calloc( nProc, sizeof( int *) ) ;
       for( i = 0 ; i < nProc ; i++ ) {
           psend[ i ] = (int*)calloc( DATA_SIZE, sizeof( int ) ) ;
           precv[ i ] = (int*)calloc( DATA_SIZE, sizeof( int ) ) ;
       }
       for( i = 0 ; i < LOOP_COUNT ; i++ ) {
          fprintf( pf, "Master : loop %d\n", i ) ;
          fflush( pf ) ;
          for( j = 1 ; j < nProc ; j++ ) {
             fprintf( pf, "  read from child %d\n", j ) ;
             fflush( pf ) ;
             status = MPI_Recv( precv[ j ], DATA_SIZE, MPI_LONG, j, MP_TAG, MPI_COMM_WORLD, MP
I_STATUS_IGNORE ) ;
             fprintf( pf, "  read from child %d done, status = %d\n", j, status ) ;
             fflush( pf ) ;
          }
          for( j = 1 ; j < nProc ; j++ ) {
             fprintf( pf, "  send to child %d\n", j ) ;
             fflush( pf ) ;
             status = MPI_Send( psend[ j ], DATA_SIZE - 1, MPI_LONG, j, MP_TAG, MPI_COMM_WORLD
 ) ;
             fprintf( pf, "  send to child %d done, status = %d\n", j, status ) ;
             fflush( pf ) ;
          }
       }
    } else {
       int  *psend ;
       int  *precv ;
         psend = (int*)calloc( DATA_SIZE, sizeof( int ) ) ;
       precv = (int*)calloc( DATA_SIZE, sizeof( int ) ) ;
       for( i = 0 ; i < LOOP_COUNT ; i++ ) {
             fprintf( pf, "  send to master\n" ) ;
             fflush( pf ) ;
             status = MPI_Send( psend, DATA_SIZE - 1, MPI_LONG, 0, MP_TAG, MPI_COMM_WORLD ) ;
             fprintf( pf, "  send to master done, status = %d\n", status ) ;
             fflush( pf ) ;
             fprintf( pf, "  read from master\n" ) ;
             fflush( pf ) ;
             status = MPI_Recv( precv, DATA_SIZE, MPI_LONG, 0, MP_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE ) ;
             fprintf( pf, "  read from master done, status = %d\n", status ) ;
             fflush( pf ) ;
       }
    }
    fclose( pf ) ;
    MPI_Finalize() ;
}



  
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