Hi!
You probably hit the nail on the head with the debugging suggestion.
After reinstalling petsc using --with-debugging=0, I'm getting more
encouraging results. For the same problem as before, but with a larger
matrix (now 10000x10000), I'm now getting the following scaling:
# n_core time (sec)
1 1540
2 870
3 660
4 571
which is much more promising than before. So thanks!
- Torquil
On 18/10/13 20:49, Jose E. Roman wrote:
No, you don't need MUMPS for ex1.c with default options.
Then I don't know what is happening. Did you build PETSc --with-debugging=0 ?
You should send performance data obtained with -log_summary, otherwise we
cannot guess what happens.
Jose
El 18/10/2013, a las 17:21, Torquil Macdonald Sørensen escribió:
It is a standard eigenvalue problem, and I'm only using default algorithm
options, so I don't think I'm using any nontrivial spectral transformation.
The program is just ex1.c from the documentation, available here:
http://www.grycap.upv.es/slepc/documentation/current/src/eps/examples/tutorials/ex1.c
FAQ #6 mentions MUMPS, which I don't have the moment, so I'll have to look into
that.
- Torquil
On 18 October 2013 16:46, Jose E. Roman <[email protected]> wrote:
El 18/10/2013, a las 16:42, Torquil Macdonald Sørensen escribió:
Hi!
I'm just starting to use SLEPc on a quad-core workstation computer (Intel Core
i5-2500 CPU @ 3.30GHz).
But I'm not getting the speedup that I was expecting, when increasing the
number of cores. E.g. when running ex1.c from the documentation, on 1, 2, 3 and
4 cores. When asking for the 500 eigenvalues of smallest magnitude, for a
5000x5000 matrix, I'm getting the following approximate timings:
# n_core time_usage
1 480s
2 400s
3 500s
4 580s
Should I not expect a speedup for n_core > 2?
The example is using the krylovschur algorithm. For all four runs, the program states
"Number of iterations of the method: 33".
I'm using PETSc 3.4.3, SLEPc 3.4.3, OpenMPI 1.6.5, and everything is compiled
using GCC 4.8.1 or 4.8.2.
Best regards
Torquil Sørensen
Is it a generalized eigenproblem and/or are you doing shift-and-invert? In that
case, have a look at FAQ #6 http://www.grycap.upv.es/slepc/documentation/faq.htm
Jose
