> On Mon, Dec 03, 2007 at 09:53:23AM +0100, Johan Hoffman wrote: >> > On Sun, Dec 02, 2007 at 06:17:35PM +0100, Johan Hoffman wrote: >> >> > >> >> > >> >> > Johan Hoffman wrote: >> >> >>> Johan Hoffman wrote: >> >> >>>> Hi all, >> >> >>>> >> >> >>>> Connected to this discussion is also the msc thesis work on >> dolfin >> >> >>>> parallization of Nicklas Jansson at KTH. He has now started >> working >> >> on >> >> >>>> this based on the updated TODO list of dolfin. He has tried to >> send >> >> an >> >> >>>> email to this list ([email protected]) but it appears that >> it >> >> is >> >> >>>> stuck >> >> >>>> in a filter awaiting moderator approval. >> >> >>> If he joins the list, he'll be able to make posts. >> >> >> >> >> >> Ok. >> >> >> >> >> >>> Maybe someone (a moderator) could >> >> >>>> help out so that we can get past this, to better coordinate >> >> >>>> parallelization efforts? >> >> >>>> >> >> >>> One point on the TODO list: we discussed some time ago the mesh >> >> >>> partitioning, and decided against ParMETIS or METIS because they >> do >> >> not >> >> >>> use a GPL (compatible) license. Magnus has implemented a nice >> >> >>> partitioning interface which uses SOCTCH which does have a GPL >> >> >>> compatible license. >> >> >> >> >> >> Ok. Does the switch to LGPL licence for dolfin make any >> difference? >> >> Or >> >> >> is >> >> >> it still a conflict? >> >> >> >> >> > >> >> > There is still a conflict. The METIS license basically says that it >> >> can >> >> > be used for non-profit purposes only, and permission is required to >> >> > re-distribute it. >> >> >> >> Ok, then there is a problem. >> >> >> >> >> About Scotch; the argument was that it lacked parallel >> partitioning, >> >> and >> >> >> a >> >> >> few other nice features of parMetis. But it seems that Scotch v5.0 >> is >> >> >> moving towards a parallel implementation as well? >> >> >> >> >> > >> >> > It does have it now. That said, I can't see us using or needing >> >> parallel >> >> > partitioning in the short- to medium-term future. >> >> >> >> Ok. Maybe we'll manage with Scotch for now then. >> >> >> >> As for parallel assembly, we will need this in the coming months, so >> we >> >> will push the fully parallel approach within Nicklas' msc project, >> >> including parallel redistribution for adaptively refined meshes >> (which >> >> parMetis seems to support nicely). >> >> >> >> /Johan >> > >> > Sounds very good, but if major changes to the Mesh classes are >> > necessary (which seems likely), I suspect I will be somewhat sensitive >> > to having all those changes pushed at once. So it would be good to >> > discuss plans for the design as early as possible so we can all feel >> > comfortable with the changes. >> > >> >> I agree. That's why the TODO list was added in the dolfin rep, and an >> accompanying dolfin-dev post was sent (...which got stuck in the >> filter). >> With a fresh dolfin-dev membership, Nicklas can resend his post where >> the >> strategy is presented in more detail, which then anyone can comment on. >> >> I would expect the plan to be rather uncontroversial, and it will fit >> nicely with the work of Magnus. >> >> /Johan > > ok, sounds good. > > Magnus is finishing his thesis at the end of January and before then > we'd like to have partitioning, communication and parallel assembly in > place. We are not planning to distribute the mesh, only to broadcast > it from one processor to all others and then the assembler skips those > cells which are not on the current processor.
Ok. > Then Nicklas can expand it to distributed meshes. (And of course the > work on the two approaches can happen in parallel.) Good. We'll keep updated through the mailinglist. /Johan > -- > Anders > _______________________________________________ > DOLFIN-dev mailing list > [email protected] > http://www.fenics.org/mailman/listinfo/dolfin-dev > _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
