[petsc-users] MUMPS error

[venkatesh g]

Hi, Thanks for the information. I now increased the workspace by adding
'-mat_mumps_icntl_14 100'

It works. However, the problem is, if I submit in 1 core I get the answer
in 200 secs, but with 4 cores and '-mat_mumps_icntl_14 100' it takes
3500secs.

My command line is: 'mpiexec -np 4 ./ex7 -f1 a2 -f2 b2 -eps_nev 1 -st_type
sinvert -eps_max_it 5000 -st_ksp_type preonly -st_pc_type lu
-st_pc_factor_mat_solver_package mumps -mat_mumps_icntl_14 100'

Kindly let me know.

Venkatesh



On Sat, May 16, 2015 at 7:10 PM, David Knezevic <david.knezevic at akselos.com>
wrote:

> On Sat, May 16, 2015 at 8:08 AM, venkatesh g <venkateshgk.j at gmail.com>
> wrote:
>
>> Hi,
>> I am trying to solving AX=lambda BX eigenvalue problem.
>>
>> A and B are of sizes 3600x3600
>>
>> I run with this command :
>>
>> 'mpiexec -np 4 ./ex7 -f1 a2 -f2 b2 -eps_nev 1 -st_type sinvert
>> -eps_max_it 5000 -st_ksp_type preonly -st_pc_type lu
>> -st_pc_factor_mat_solver_package mumps'
>>
>> I get this error: (I get result only when I give 1 or 2 processors)
>> Reading COMPLEX matrices from binary files...
>> [0]PETSC ERROR: --------------------- Error Message
>> ------------------------------------
>> [0]PETSC ERROR: Error in external library!
>> [0]PETSC ERROR: Error reported by MUMPS in numerical factorization phase:
>> INFO(1)=-9, INFO(2)=2024
>>
>
>
> The MUMPS error types are described in Chapter 7 of the MUMPS manual. In
> this case you have INFO(1)=-9, which is explained in the manual as:
>
> "–9 Main internal real/complex workarray S too small. If INFO(2) is
> positive, then the number of entries that are missing in S at the moment
> when the error is raised is available in INFO(2). If INFO(2) is negative,
> then its absolute value should be multiplied by 1 million. If an error –9
> occurs, the user should increase the value of ICNTL(14) before calling the
> factorization (JOB=2) again, except if ICNTL(23) is provided, in which case
> ICNTL(23) should be increased."
>
> This says that you should use ICTNL(14) to increase the working space size:
>
> "ICNTL(14) is accessed by the host both during the analysis and the
> factorization phases. It corresponds to the percentage increase in the
> estimated working space. When significant extra fill-in is caused by
> numerical pivoting, increasing ICNTL(14) may help. Except in special cases,
> the default value is 20 (which corresponds to a 20 % increase)."
>
> So, for example, you can avoid this error via the following command line
> argument to PETSc: "-mat_mumps_icntl_14 30", where 30 indicates that we
> allow a 30% increase in the workspace instead of the default 20%.
>
> David
>
>
>
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