[petsc-users] PetscInt overflow

[Jan Grießer]

Thiis i already did with mpiexec -n 20 ... and there the error occured. I
was also a little bit surprised that this error occured. Our computation
nodes have 20 cores with 6GB RAM.
Is PETSc/ SLEPc saving the dense eigenvector error in one core ?


Am Fr., 19. Okt. 2018 um 12:52 Uhr schrieb Jan Grießer <
griesser.jan at googlemail.com>:

> Thiis i already did with mpiexec -n 20 ... and there the error occured. I
> was also a little bit surprised that this error occured. Our computation
> nodes have 20 cores with 6GB RAM.
> Is PETSc/ SLEPc saving the dense eigenvector error in one core ?
>
> Am Fr., 19. Okt. 2018 um 11:08 Uhr schrieb Jose E. Roman <
> jroman at dsic.upv.es>:
>
>> No, I mean to run in parallel:
>>
>> $ mpiexec -n 8 python ex1.py
>>
>> Jose
>>
>>
>> > El 19 oct 2018, a las 11:01, Jan Grießer <griesser.jan at googlemail.com>
>> escribió:
>> >
>> > With more than 1 MPI process you mean i should use spectrum slicing in
>> divide the full problem in smaller subproblems?
>> > The --with-64-bit-indices is not a possibility for me since i
>> configured petsc with mumps, which does not allow to use the 64-bit version
>> (At least this was the error message when i tried to configure PETSc )
>> >
>> > Am Mi., 17. Okt. 2018 um 18:24 Uhr schrieb Jose E. Roman <
>> jroman at dsic.upv.es>:
>> > To use BVVECS just add the command-line option -bv_type vecs
>> > This causes to use a separate Vec for each column, instead of a single
>> long Vec of size n*m. But it is considerably slower than the default.
>> >
>> > Anyway, for such large problems you should consider using more than 1
>> MPI process. In that case the error may disappear because the local size is
>> smaller than 768000.
>> >
>> > Jose
>> >
>> >
>> > > El 17 oct 2018, a las 17:58, Matthew Knepley <knepley at gmail.com>
>> escribió:
>> > >
>> > > On Wed, Oct 17, 2018 at 11:54 AM Jan Grießer <
>> griesser.jan at googlemail.com> wrote:
>> > > Hi all,
>> > > i am using slepc4py and petsc4py to solve for the smallest real
>> eigenvalues and eigenvectors. For my test cases with a matrix A of the size
>> 30k x 30k solving for the smallest soutions works quite well, but when i
>> increase the dimension of my system to around A = 768000 x 768000 or 3
>> million x 3 million and ask for the smallest real 3000 (the number is
>> increasing with increasing system size) eigenvalues and eigenvectors i get
>> the output (for the 768000):
>> > >  The product 4001 times 768000 overflows the size of PetscInt;
>> consider reducing the number of columns, or use BVVECS instead
>> > > i understand that the requested number of eigenvectors and
>> eigenvalues is causing an overflow but i do not understand the solution of
>> the problem which is stated in the error message. Can someone tell me what
>> exactly BVVECS is and how i can use it? Or is there any other solution to
>> my problem ?
>> > >
>> > > You can also reconfigure with 64-bit integers: --with-64-bit-indices
>> > >
>> > >   Thanks,
>> > >
>> > >     Matt
>> > >
>> > > Thank you very much in advance,
>> > > Jan
>> > >
>> > >
>> > >
>> > > --
>> > > 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
>> > >
>> > > https://www.cse.buffalo.edu/~knepley/
>> >
>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20181019/6f60a742/attachment.html>