To use the multi-model mechanism in Carpet: (1) Arrange for mpirun to start the Cactus run with different parameter files for different MPI ranks. All MPI implementations I know of have a mechanism for this. You may or may not want to use different executables as well.
(2) In the parameter files, set the parameter Carpet::model to different strings. (3) Carpet will then group all MPI ranks by this parameter's value, create a communicator for each of these, and start independent runs for each. (4) So far, all you've done is starting several completely unrelated and independent simulations with one mpirun call. (5) Carpet offers an aliased function GetMPICommUniverse that returns the original MPI communicator that allows all processes to communicate. (Compare with GetMPICommWorld.) Note that there is no implicit or implied synchronization between the different worlds; this is your responsibility. (7) Thorn CactusNumerical/Slab has a mechanism for passing an MPI communicator that it should use, allowing you to transfer hyperslabs between worlds. Other thorns may be extended similarly if necessary. -erik On Wed, Apr 22, 2015 at 1:10 AM, Ian Hinder <[email protected]> wrote: > > On 22 Apr 2015, at 02:03, Erik Schnetter <[email protected]> wrote: > > > For the record: Roland and I discussed this in person. > > Hi Erik and Roland, > > I am also interested; maybe you could write a very short summary of your > conclusions? > > > > > -erik > > > > On Mon, Apr 20, 2015 at 7:39 PM, Roland Haas < > [email protected]> wrote: > > Hello all, > > > > is there any documentation / examples on how to use the multi-model code > > in Carpet? In particular I am interested (but don't plan to work on it > > any time soon, so no hurry) in having multiple Llama grids active at the > > same time to interpolate data from one to the other. > > > > Yours, > > Roland > > > > -- > > My email is as private as my paper mail. I therefore support encrypting > > and signing email messages. Get my PGP key from http://keys.gnupg.net. > > > > > > > > > > > > > > _______________________________________________ > > Developers mailing list > > [email protected] > > http://www.cactuscode.org/mailman/listinfo/developers > > > > > > > > > > -- > > Erik Schnetter <[email protected]> > > http://www.perimeterinstitute.ca/personal/eschnetter/ > > _______________________________________________ > > Developers mailing list > > [email protected] > > http://www.cactuscode.org/mailman/listinfo/developers > > -- > Ian Hinder > http://members.aei.mpg.de/ianhin > > -- Erik Schnetter <[email protected]> http://www.perimeterinstitute.ca/personal/eschnetter/
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