[petsc-users] MUMPS error

[Matthew Knepley]

On Mon, May 18, 2015 at 8:29 AM, venkatesh g <venkateshgk.j at gmail.com>
wrote:

> Hi I have attached the performance logs for 2 jobs on different
> processors. I had to increase the workspace icntl(14) when I submit on more
> cores since it is failing with small value of icntl(14).
>
> 1. performance_log1.txt is run on 8 cores (option given
> -mat_mumps_icntl_14 200)
> 2. performance_log2.txt is run on 2 cores (option given
> -mat_mumps_icntl_14 85  )
>

1) Your number of iterates increased from 7600 to 9600, but that is a
relatively small effect

2) MUMPS is just taking a lot longer to do forward/backward solve. You
might try emailing
the list for them. However, I would bet that your system has enough
bandwidth for 2 procs
and not much more.

  Thanks,

     Matt


> Venkatesh
>
> On Sun, May 17, 2015 at 6:13 PM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>> On Sun, May 17, 2015 at 1:38 AM, venkatesh g <venkateshgk.j at gmail.com>
>> wrote:
>>
>>> 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.
>>>
>>
>> Send the output of -log_summary for all performance queries. Otherwise we
>> are just guessing.
>>
>>     Matt
>>
>> 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
>>>>
>>>>
>>>>
>>>
>>
>>
>> --
>> 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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