http://www.mcs.anl.gov/research/projects/mpi/usingmpi2/examples/starting/main.htm

/* example of sequential Unix write into a common file */

mpirun -np 4 ./io1

/* example of parallel Unix write into separate files */

mpirun -np 4 ./io2

/* example of parallel MPI write into separate files */

mpirun -np 4 ./io3

/* example of parallel MPI write into a single file */

mpirun -np 4 ./io4

/* example of parallel MPI write into a single file (arbitrary num of procs) */

mpirun -np 4 ./io5

/* parallel MPI read with arbitrary number of processes*/

mpirun -np 4 ./io6

python http://chrisjbutler.wordpress.com/2010/09/23/mpi4py-parallel-io-example/

all in one

mpirun -np 4 ./io4.py

all in all

mpirun -np 4 ./io3.py

1. les slaves envoient tout au master (avec MPI/IO ?)

nouvelle fct

io.ReadBlock -> io.readblock

			-> mpi_ReadAndSendBlock

io.ReadDataBlock -> io.readblock

			-> mpi_ReadAndSendArray

io.WriteArray -> writeblock

			-> mpi_GatherAndWriteArray

io.WriteBlock

new function:

• fct that write a simple header
• may add header
• master read a block and send it
• master gather a block and write it
• read an array and send it
• write an array and send it

2. test a faire rapidement ###########

mpirun -np 4 io7.py mpirun -np 4 io4.py mpirun -np 4 io3.py

cat pytest-io3.0 pytest-io3.1 pytest-io3.2 pytest-io3.3 > pytest-io3.dat

see : regor:/home/revaz/io/parallelio/

pos

• gas
• stars
• halo

on veut :

header		t0
pos-gas		t0	
pos-gas		t1
pos-gas		t2
pos-stars		t0
pos-stars		t1
pos-stars		t2
pos-halo		t0
pos-halo		t1
pos-halo		t2
header  		t0

WriteGadgetBlock(pos,npart)

WriteGadgetBlock
  WriteHeader
  
  WriteArray(pos[])    
  WriteArray(pos[])
  WriteArray(pos[])

  WriteHeader

2. proposition ######

pio='yes' mode='mpiio' (separate files)

lecture/ecriture en //, avec mpiio

pio='yes' mode='normal' (separate files)

lecture/ecriture en //, bcast sur master

pio='no' mode='mpiio' (single file)

pio='no' mode='normal' (single file)

lecture/ecriture sur un seul fichier
tout passe par le master

def WriteArray(f,data,add_header=False,x64=False,byteorder=sys.byteorder)

f = file or MPI.File
--> il faut donner le mode
    pio      -> trouver comment donner un defaut
    piomode  -> trouver comment donner un defaut
   
   
   
   
if pio=='yes' and piomode=='mpiio':

mpirun -np 2 test_io.py