[petsc-users] Error using MUMPS to solve large linear system

[Samar Khatiwala]

Hi Sherry,

Thanks for the offer to help!

I tried superlu_dist again and it crashes even more quickly than MUMPS with just the following error:

ERROR: 0031-250  task 128: Killed

Absolutely nothing else is written out to either stderr or stdout. This is with -mat_superlu_dist_statprint. 
The program works fine on a smaller matrix.

This is the sequence of calls:

KSPSetType(ksp,KSPPREONLY);
PCSetType(pc,PCLU);
PCFactorSetMatSolverPackage(pc,MATSOLVERSUPERLU_DIST);
KSPSetFromOptions(ksp);
PCSetFromOptions(pc);
KSPSolve(ksp,b,x);

All of these successfully return *except* the very last one to KSPSolve.

Any help would be appreciated. Thanks!

Samar

On Feb 24, 2014, at 3:58 PM, Xiaoye S. Li <xsli at lbl.gov> wrote:

> Samar:
> If you include the error message while crashing using superlu_dist, I probably know the reason.  (better yet, include the printout before the crash. )
> 
> Sherry
> 
> 
> On Mon, Feb 24, 2014 at 9:56 AM, Hong Zhang <hzhang at mcs.anl.gov> wrote:
> Samar :
> There are limitations for direct solvers. 
> Do not expect any solver can be used on arbitrarily large problems.
> Since superlu_dist also crashes, direct solvers may not be able to work on your application. 
> This is why I suggest to increase size incrementally. 
> You may have to experiment other type of solvers.
> 
> Hong
> 
> Hi Hong and Jed,
> 
> Many thanks for replying. It would indeed be nice if the error messages from MUMPS were less cryptic!
> 
> 1) I have tried smaller matrices although given how my problem is set up a jump is difficult to avoid. But a good idea 
> that I will try.
> 
> 2) I did try various ordering but not the one you suggested.
> 
> 3) Tracing the error through the MUMPS code suggest a rather abrupt termination of the program (there should be more 
> error messages if, for example, memory was a problem). I therefore thought it might be an interface problem rather than 
> one with mumps and turned to the petsc-users group first. 
> 
> 4) I've tried superlu_dist but it also crashes (also unclear as to why) at which point I decided to try mumps. The fact that both 
> crash would again indicate a common (memory?) problem.
> 
> I'll try a few more things before asking the MUMPS developers.
> 
> Thanks again for your help!
> 
> Samar
> 
> On Feb 24, 2014, at 11:47 AM, Hong Zhang <hzhang at mcs.anl.gov> wrote:
> 
>> Samar:
>> The crash occurs in 
>> ...
>> [161]PETSC ERROR: Error in external library!
>> [161]PETSC ERROR: Error reported by MUMPS in numerical factorization phase: INFO(1)=-1, INFO(2)=48
>>  
>> for very large matrix, likely memory problem as you suspected. 
>> I would suggest 
>> 1. run problems with increased sizes (not jump from a small one to a very large one) and observe memory usage using
>> '-ksp_view'.
>>    I see you use '-mat_mumps_icntl_14 1000', i.e., percentage of estimated workspace increase. Is it too large?
>>    Anyway, this input should not cause the crash, I guess.
>> 2. experimenting with different matrix ordering -mat_mumps_icntl_7 <> (I usually use sequential ordering 2) 
>>     I see you use parallel ordering -mat_mumps_icntl_29 2.
>> 3. send bug report to mumps developers for their suggestion.
>> 
>> 4. try other direct solvers, e.g., superlu_dist.
>>  
>> …
>> 
>> etc etc. The above error I can tell has something to do with processor 48 (INFO(2)) and so forth but not the previous one.
>> 
>> The full output enabled with -mat_mumps_icntl_4 3 looks as in the attached file. Any hints as to what could be giving this
>> error would be very much appreciated.
>>  
>> I do not know how to interpret this  output file. mumps developer would give you better suggestion on it.
>> I would appreciate to learn as well :-)
>> 
>> Hong
> 
> 
> 

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