code_saturne User's Forum

Hello,

I wanted to ask which version of METIS and/or ParMETIS you would recommend. On the upstream website they offer version 5.0.2 for METIS and 4.0.2 for ParMETIS. The Debian/Ubuntu repositories only contain version 4.1 and 3.1.1. The developer changelog says, that these versions are from 2003/2004.
Do these old versions work properly with Code_Saturne (and SYRTHES) or would you recommend to use the upstream versions? Do you have an idea, why there are no newer versions in Debian? Is it because of license issues?

Best regards,

Martin

Hello,

Yes, Code_Saturne can build both with METIS 4 / ParMETIS 3 and METIS 5 / ParMETIS 4, as well as SCOTCH or PT-SCOTCH (at least versions 5.10 to 5.12).

We are waiting a bit to remove support for the old versions (though as soon as Debian upgrades to the newer versions, we will be tempted to do it).

I do not know if the lack of upgrade is directly due to licencing issues (the METIS licence has barely changed, an was already non-free), or due to the fact that SCOTCH is now available, with a free licence, (CeCiLL, very similar to GPL) and provides METIS compatibility options (though Code_Saturne can directly support SCOTCH, allowing it to be build simultaneously with SCOTCH and METIS for those who want to compare the 2).

In any case, for large meshes (25 million or more cells), serial METIS4 can run into memory management issues, while METIS 5 does better. On several tests, SCOTCH and PT-SCOTCH also seem to require less memory than METIS or ParMETIS, though it may be slightly slower. Partitioning quality is comparable.

Best regards,

Yvan