[petsc-users] Unequal sparse matrix row distribution for MPI MatMult

Matthew Knepley knepley at gmail.com
Wed Apr 1 06:42:44 CDT 2015


On Tue, Mar 31, 2015 at 11:05 PM, Steena M <stm8086 at yahoo.com> wrote:

> Thanks Matt. I'm still getting the malloc error
>

If you are loading a matrix, its just

   CHKERRQ( MatCreate(comm, &A));
CHKERRQ( MatLoad(A,fd));

   Matt


> [0]PETSC ERROR: Argument out of range!
> [0]PETSC ERROR: New nonzero at (2,18) caused a malloc!
>
> and
>
> a new incorrect matrix file error:
>
> [0]PETSC ERROR: Unexpected data in file!
> [0]PETSC ERROR: not matrix object!
>
> Maybe the order of calls is mixed up. This is the code snippet:
>
> if (rank ==0)
> {
>  PetscPrintf (PETSC_COMM_WORLD,"\n On rank %d ", rank);
>
> CHKERRQ(MatSetSizes(A, 15, PETSC_DETERMINE, 20, 20));
> CHKERRQ(MatSetType(A, MATMPIBAIJ));
> CHKERRQ( MatMPIBAIJSetPreallocation(A,1,1,NULL,1,NULL));
> CHKERRQ( MatLoad(A,fd));
>  CHKERRQ(MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE));
> }
>  else
> {
> PetscPrintf (PETSC_COMM_WORLD,"\n On rank %d ", rank);
>  CHKERRQ( MatSetSizes(A, 5, PETSC_DETERMINE, 20, 20) );
> CHKERRQ(MatSetType(A, MATMPIBAIJ));
> CHKERRQ( MatMPIBAIJSetPreallocation(A,1,1,NULL,1,NULL));
> CHKERRQ(MatLoad(A,fd));
> CHKERRQ(MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE));
>  }
>
> Is there something I'm missing?
>
> Thanks,
> Steena
>
>
>
>
>   On Tuesday, March 31, 2015 6:10 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>
> On Tue, Mar 31, 2015 at 6:51 PM, Steena M <stm8086 at yahoo.com> wrote:
>
> Thanks Barry. I'm still getting the malloc error with NULL. Is there a way
> to distribute the matrix without explicit preallocation? Different matrices
> will be loaded during runtime and assigning preallocation parameters would
> mean an additional preprocessing step.
>
>
> 1) MatSetOption(MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE)
>
> 2) Note that this is never ever ever more efficient than making another
> pass and preallocating
>
>   Thanks,
>
>      Matt
>
> --------------------------------------------
> On Sun, 3/29/15, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>  Subject: Re: [petsc-users] Unequal sparse matrix row distribution for MPI
> MatMult
>  To: "Steena M" <stm8086 at yahoo.com>
>  Cc: "Matthew Knepley" <knepley at gmail.com>, petsc-users at mcs.anl.gov
>  Date: Sunday, March 29, 2015, 9:26 PM
>
>
>  > On
>  Mar 29, 2015, at 11:05 PM, Steena M <stm8086 at yahoo.com>
>  wrote:
>  >
>  > Thanks
>  Matt. I used PETSC_DETERMINE but I'm now getting an
>  allocation-based error:
>  >
>  > [0]PETSC ERROR: ---------------------
>  Error Message ------------------------------------
>  > [0]PETSC ERROR: Argument out of range!
>  > [0]PETSC ERROR: New nonzero at (2,18)
>  caused a malloc!
>  > [0]PETSC ERROR:
>  ------------------------------------------------------------------------
>  >
>  > I tried
>  preallocating on each rank for the diagonal and off diagonal
>  section of the matrix as the next step  My current
>  approximations for preallocation
>  >
>  > CHKERRQ(
>  MatMPIBAIJSetPreallocation(A,1,5,PETSC_DEFAULT,5,PETSC_DEFAULT));
>
>
>     These
>  arguments where you pass PETSC_DEFAULT are expecting a
>  pointer not an integer. You can pass NULL in those
>  locations. Though it is better to provide the correct
>  preallocation rather than some defaults.
>
>    Barry
>
>  >
>  > are throwing segmentation errors.
>  >
>  > [0]PETSC ERROR:
>  Caught signal number 11 SEGV: Segmentation Violation,
>  probably memory access out of range
>  >
>  > Any insights into what I'm doing
>  wrong?
>  >
>  > Thanks,
>  > Steena
>  >
>  >
>  >
>  > On Sun, 3/29/15, Matthew Knepley <knepley at gmail.com>
>  wrote:
>  >
>  > Subject:
>  Re: [petsc-users] Unequal sparse matrix row distribution for
>  MPI MatMult
>  > To: "Steena M"
>  <stm8086 at yahoo.com>
>  > Cc: "Barry Smith" <bsmith at mcs.anl.gov>,
>  petsc-users at mcs.anl.gov
>  > Date: Sunday, March 29, 2015, 10:02 PM
>  >
>  > On Sun, Mar 29, 2015
>  at
>  > 9:56 PM, Steena M <stm8086 at yahoo.com>
>  > wrote:
>  > Hi
>  > Barry,
>  >
>  >
>  >
>  > I am trying to partition a 20 row and 20
>  col sparse matrix
>  > between two procs
>  such that proc 0 has 15 rows and 20 cols
>  > and proc 1 has 5 rows and 20 cols. The
>  code snippet:
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>     CHKERRQ(MatCreate(PETSC_COMM_WORLD,&A));
>  //
>  > at runtime: -matload_block_size 1
>  >
>  >
>  >
>  >
>  >
>  >
>     if (rank ==0)
>  >
>  >         {
>  >
>  >
>     CHKERRQ( MatSetSizes(A, 15, 20, 20,
>  > 20) ); //rank 0 gets 75% of the rows
>  >
>  >
>     CHKERRQ( MatSetType(A, MATMPIBAIJ)
>  > );
>  >
>  >                 CHKERRQ(
>  MatLoad(A,fd) );
>  >
>  >          }
>  >
>  >
>  >
>  >         else
>  >
>  >
>     {
>  >
>  >
>                 CHKERRQ( MatSetSizes(A, 5,
>  20, 20,
>  > 20) ); //rank 1 gets 25% of the
>  rows
>  >
>  >
>           CHKERRQ( MatSetType(A, MATMPIBAIJ)
>  > );
>  >
>  >                 CHKERRQ(
>  MatLoad(A,fd) );
>  >
>  >       }
>  >
>
>  >
>  >
>  > This throws the following error (probably
>  from psplit.c):
>  >
>  >
>  [1]PETSC ERROR: --------------------- Error Message
>  > ------------------------------------
>  >
>  > [1]PETSC ERROR:
>  Nonconforming object sizes!
>  >
>  > [1]PETSC ERROR: Sum of local lengths 40
>  does not equal
>  > global length 20, my
>  local length 20
>  >
>  >   likely a call to
>  VecSetSizes() or MatSetSizes() is
>  >
>  wrong.
>  >
>  > See
>  http://www.mcs.anl.gov/petsc/documentation/faq.html#split!
>  >
>  >
>  >
>  > This error printout
>  doesn't quite make sense to me.
>  >
>  I'm trying to specify a total matrix size of 20x20...
>  I
>  > haven't yet figured out where the
>  '40' comes
>  > from in the error
>  message.
>  >
>  >
>  >
>  > Any thoughts on what
>  might be going wrong?
>  >
>  > Its the column specification. Just
>  > use PETSC_DETERMINE for the local columns
>  since all our
>  > sparse matrixformats are
>  row divisions
>  > anyway.
>  >
>  > Thanks,
>  >
>  >  Matt
>  > Thanks in advance,
>  >
>
>  > Steena
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  --------------------------------------------
>  >
>  > On Sun, 3/22/15,
>  Barry Smith <bsmith at mcs.anl.gov>
>  > wrote:
>  >
>  >
>  >
>  >  Subject: Re: [petsc-users] Unequal
>  sparse matrix row
>  > distribution for MPI
>  MatMult
>  >
>  >  To:
>  "Steena M" <stm8086 at yahoo.com>
>  >
>  >  Cc: petsc-users at mcs.anl.gov
>  >
>  >  Date: Sunday,
>  March 22, 2015, 3:58 PM
>  >
>  >
>  >
>  >
>  >
>  >
>  >
>  >  Steena,
>  >
>  >
>  >
>  >     I am
>  >
>
>  >  a little unsure of your question.
>
>  >
>  >
>  >
>  >     1)
>  you can create a MPIBAIJ
>  >
>  >  matrix with any distribution of block
>  rows per process
>  > you
>  >
>  >  want, just set the
>  local row size for each process to
>  >
>  be
>  >
>  >  what you
>  like.  Use MatCreateVecs() to get
>  >
>  correspondingly
>  >
>  >
>  laid out vectors.
>  >
>  >
>
>  >
>  >
>     or 2) if you have a MPIBAIJ
>  >
>  >  matrix with
>  "equal" row layout and you want a
>  > new
>  >
>  >  one with uneven row layout you can
>  simply use
>  >
>  >
>  MatGetSubMatrix() to create that new matrix.
>  >
>  >
>  >
>  >    Barry
>  >
>  >
>  >
>  >  Unless you have
>  another reason to have the
>  >
>  >  matrix with an equal number row layout I
>  would just
>  > generate
>  >
>  >  the matrix with
>  the layout you want.
>  >
>  >
>  >
>  >
>  >
>  >  > On Mar 22, 2015, at 5:50 PM, Steena
>  M
>  >
>  >  <stm8086 at yahoo.com>
>  >
>  >  wrote:
>  >
>  >  >
>  >
>  >  > Hello,
>  >
>  >  >
>  >
>  >  > I need to
>  distribute
>  >
>  >  a
>  sparse matrix such that each proc owns an unequal
>  > number
>  >
>  >  of blocked rows before I proceed with
>  MPI MatMult. My
>  >
>  >
>  initial thoughts on doing this:
>  >
>  >  >
>  >
>  >  > 1) Use  MatGetSubMatrices() on the
>  test
>  >
>  >  MATMPIBAIJ
>  matrix to produce a new matrix where each
>  > proc
>  >
>  >  has an unequal number of rows.
>  >
>  >  >
>  >
>  >  > 2) Provide
>  scatter context for vector X
>  >
>  >  (for MatMult )using IS iscol from
>  MatGetSubMatrices()
>  > while
>  >
>  >  creating the
>  vector X.
>  >
>  >
>  >
>  >
>  >  > 3)
>  Call MatMult()
>  >
>  >
>  >
>  >
>  >  > Will
>  MatMult_MPIBAIJ continue to scatter
>  >
>  >  this matrix and vector such that each
>  proc will own an
>  > equal
>  >
>  >  number of matrix
>  rows and corresponding diagonal vector
>  >
>
>  >  elements? Should I write my own
>  MPIMatMult function to
>  >
>  >  retain my redistribution of the matrix
>  and vector?
>  >
>  >
>  >
>  >
>  >  >
>  Thanks in
>  >
>  >
>  advance,
>  >
>  >  >
>  Steena
>  >
>  >
>  >
>  >
>  >
>  >
>  > --
>  > What most
>  experimenters
>  > take for granted before
>  they begin their experiments is
>  >
>  infinitely more interesting than any results to which
>  their
>  > experiments lead.
>  > -- Norbert
>  > Wiener
>
>  >
>
>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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