[Trilinos-Users] [EXTERNAL] Threading for incomplete LU in Ifpack2

Rajamanickam, Sivasankaran srajama at sandia.gov
Tue Dec 13 13:21:18 EST 2016

Wen Yan,

   The ILU(k) multithreading is being planned for later this year. ILU(t) multithreading is trickier.

   If you want to use a multithreaded local solve right away, you could try SGS now. There is an experimental capability available now. What is the problem you are trying to solve ?


From: Trilinos-Users <trilinos-users-bounces at trilinos.org> on behalf of Wen Yan <wenyan4work at gmail.com>
Sent: Tuesday, December 13, 2016 9:32 AM
To: trilinos-users at trilinos.org
Subject: [EXTERNAL] [Trilinos-Users] Threading for incomplete LU in Ifpack2

Hi Trilinos Users,

I was wondering if the RILUK and ILUT methods in Ifpack2 support multithreading. The online doxygen webpage for Ifpack2 says " Finally, Ifpack2<https://trilinos.org/docs/dev/packages/ifpack2/doc/html/namespaceIfpack2.html>'s algorithms use and produce Tpetra objects, so you can exploit Tpetra's hybrid (MPI + threads) parallelism features without effort."

However I see that RILUK and ILUT both use only one CPU core in the compute() phase for my test program with a sparse matrix dimension at around 10^4~10^5. The nnz of entries per line is around 10%. I have compiled trilinos with openmp support and enabled openmp by setting OMP_NUM_THREADS. Multithreading is confirmed in other packages in test programs in 'make test'.

Is it possible to activate multithreading RILUK and ILUT in Ifpack2? Or is it possible to call SuperLU_MT or SuperLU_DIST through the Amesos2 interface?

Thank you,
Wen Yan
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