[petsc-users] MUMPS error

[venkatesh g]

Hi,
I have emailed the mumps-user list.
Actually the cluster has 8 nodes with 16 cores, and other codes scale well.
I wanted to ask if this job takes much time, then if I submit on more
cores, I have to increase the icntl(14).. which would again take long time.

So is there another way ?

cheers,
Venkatesh

On Mon, May 18, 2015 at 7:16 PM, Matthew Knepley <knepley at gmail.com> wrote:

> 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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