[petsc-users] Out of memory - diffusion equation eigenvalues

[Rodrigo Piccinini]

Hello,

The number of unknowns after discretization is 60x85x220 = 1.12 million
nodes.
This should be the size of an eigenfunction vector in 3d.

Em seg, 1 de jul de 2019 às 20:26, Mark Adams <mfadams at lbl.gov> escreveu:

> 3D uses a lot more memory. This is a crazy number (18446744069467867136).
> How large is your system?
>
> On Mon, Jul 1, 2019 at 7:20 PM Rodrigo Piccinini via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
>> Hello,
>>
>> I'm trying to solve for the first ten smallest eigenvalues of a diffusion
>> equation in a 3d heterogeneous medium (varying diffusion coefficient), but
>> I'm getting an error message:
>>
>> Traceback (most recent call last):
>>>   File "eigendrake_spe10_v2.py", line 121, in <module>
>>>     es.solve()
>>>   File "SLEPc/EPS.pyx", line 1132, in slepc4py.SLEPc.EPS.solve
>>> petsc4py.PETSc.Error: error code 55
>>> [0] EPSSolve() line 136 in
>>> /tmp/pip-req-build-6t_4bkg3/src/eps/interface/epssolve.c
>>> [0] EPSSetUp() line 269 in
>>> /tmp/pip-req-build-6t_4bkg3/src/eps/interface/epssetup.c
>>> [0] STSetUp() line 271 in
>>> /tmp/pip-req-build-6t_4bkg3/src/sys/classes/st/interface/stsolve.c
>>> [0] STSetUp_Shift() line 119 in
>>> /tmp/pip-req-build-6t_4bkg3/src/sys/classes/st/impls/shift/shift.c
>>> [0] KSPSetUp() line 391 in
>>> /tmp/pip-req-build-070lpqqd/src/ksp/ksp/interface/itfunc.c
>>> [0] PCSetUp() line 932 in
>>> /tmp/pip-req-build-070lpqqd/src/ksp/pc/interface/precon.c
>>> [0] PCSetUp_LU() line 99 in
>>> /tmp/pip-req-build-070lpqqd/src/ksp/pc/impls/factor/lu/lu.c
>>> [0] MatLUFactorSymbolic() line 3111 in
>>> /tmp/pip-req-build-070lpqqd/src/mat/interface/matrix.c
>>> [0] MatLUFactorSymbolic_SeqAIJ() line 366 in
>>> /tmp/pip-req-build-070lpqqd/src/mat/impls/aij/seq/aijfact.c
>>> [0] PetscMallocA() line 390 in
>>> /tmp/pip-req-build-070lpqqd/src/sys/memory/mal.c
>>> [0] MatLUFactorSymbolic_SeqAIJ() line 366 in
>>> /tmp/pip-req-build-070lpqqd/src/mat/impls/aij/seq/aijfact.c
>>> [0] Out of memory. Allocated: 0, Used by process: 14097043456
>>> [0] Memory requested 18446744069467867136
>>
>>
>> I'm using code from Firedrake Project <https://www.firedrakeproject.org/>
>> (finite-element method) to discretize the equations.
>> My code is available here:
>> https://github.com/rbpiccinini/codes/blob/master/eigendrake/eigendrake_spe10_v2.py
>>
>> The code was run with 64GB available as RAM memory. The requested memory
>> seems to be abnormally high, though.
>> I'm able to solve for the eigenvalues of a 2d smaller problem. However,
>> if I try to solve the 3d problem, I get the out of memory error.
>>
>> Could anybody help me understand the issue?
>>
>> Thanks in advance.
>>
>> --
>> Rodrigo
>>
>

-- 


--
Rodrigo
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