[petsc-users] MUMPS error

[Barry Smith]

   Run the streams benchmark on this system and send the results. http://www.mcs.anl.gov/petsc/documentation/faq.html#computers


> On May 18, 2015, at 11:14 AM, venkatesh g <venkateshgk.j at gmail.com> wrote:
> 
> 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
>