[petsc-users] mumps freezes for bigger problems

[Jed Brown]

On Fri, Dec 23, 2011 at 16:36, Dominik Szczerba <dominik at itis.ethz.ch>wrote:

> I tried all of your suggestions, unfortunately, still get MUMPS not
> moving an inch. Running in debugger and interrupting reveals:
>
> 0x000000000139d233 in dgemm (transa=..., transb=..., m=3621, n=3621, k=251,
>    alpha=-1, a=..., lda=3872, b=..., ldb=3872, beta=1, c=..., ldc=3872,
>    _transa=1, _transb=1) at dgemm.f:242
> 242                                   C(I,J) = C(I,J) + TEMP*A(I,L)
>
> So it's seems to be doing something, but on a small problem it takes a
> few minutes, so I do not expect a problem of 2-3 times the size take
> longer than a day...
>

Is one mesh just a refined version of the other, or is the shape different?
Factorization time should be roughly quadratic in problem size for 3D
problems.

If the increased fill caused the system to run out of physical memory and
start swapping, then it would not be surprising for it to take days.
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