[petsc-users] mumps solve with same nonzero pattern

[Alexander Grayver]

This is not quite normal.

Right now I'm dealing with 0.65 million problem and it takes 15 secs for 
symbolic factorization to be done using 64 cores (four 16x cores nodes).

As Hong suggested you should try different ordering techniques. Usually 
metis is among the best (-mat_mumps_icntl_7 5). And also any timings is 
better to do in release version (--with-debugging=0 flag for configure).

You should be able to get some output and statistics from MUMPS with this:
-mat_mumps_icntl_3 2 -mat_mumps_icntl_4 2

If you don't read MUMPS manual for that. Without any output from MUMPS 
it is not really clear what happens.

On 27.04.2012 19:49, Wen Jiang wrote:
> Thanks for your reply. I also tested the exactly same problem with 
> SUPERLU. The mumps and superlu dist both are using sequential symbolic 
> factorization. However, superlu dist takes only 20 seconds but mumps 
> takes almost 700 seconds. I am wondering whether such a big difference 
> is possible. Do those two direct solver use quite different algorithm?
>
> And also since I might have the same nonzero structure system to be 
> solved many times at different places. I am wondering whether I could 
> save the symbolic factorization output somewhere and then read them as 
> the input for future solving. Thanks.
>
> Regards,
> Wen
>


-- 
Regards,
Alexander