[petsc-users] Memory optimization

[Perceval Desforges]

Hello all, 

I am trying to obtain all the eigenvalues in a certain interval for a
fairly large matrix (1000000 * 1000000). I therefore use the spectrum
slicing method detailed in section 3.4.5 of the manual. The calculations
are run on a processor with 20 cores and 96 Go of RAM. 

The options I use are : 

-bv_type vecs  -eps_krylovschur_detect_zeros 1 -mat_mumps_icntl_13 1
-mat_mumps_icntl_24 1 -mat_mumps_cntl_3 1e-12 

However the program quickly crashes with this error: 

slurmstepd: error: Step 2115.0 exceeded virtual memory limit (312121084
> 107317760), being killed 

I've tried reducing the amount of memory used by slepc with the
-mat_mumps_icntl_14 option by setting it at -70 for example but then I
get this error: 

[1]PETSC ERROR: Error in external library
[1]PETSC ERROR: Error reported by MUMPS in numerical factorization
phase: INFOG(1)=-9, INFO(2)=82733614 

which is an error due to setting the mumps icntl option so low from what
I've gathered. 

Is there any other way I can reduce memory usage? 

Thanks, 

Regards, 

Perceval, 

P.S. I sent the same email a few minutes ago but I think I made a
mistake in the address, I'm sorry if I've sent it twice.
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