On 20/07/11 22:28, Johan Hake wrote: > Hello! > > I know this has been discussed earlier, but I cannot find a bug or blueprint > reported for it. > > Let say I have a MixedSpace containing several global dofs (Real spaces) and > one CG. Even if I define a form using functions defined only on the CG space > it takes literally forever to assemble... This is because for each cell, a > bunch of zeros are added to the global matrix, as the dofmap which defines > the > element matrix, is based on the whole MixedSpace. It would be _really_ nice > if > the size of the element matrix was based on the actuall dofs that get > assembled. >
As a quick fix, try using the Epetra backend. My experience is that it's much faster for this type of case. It must use a different search method for insertion than PETSc. > Garth has previously mentioned that this is done to simplify the assemble > interface, which is understandable. However, beside fixing assemble of global > dofs in paralell this is my biggest wish for ufc/ffc/dolfin at the moment :) > > Unfortunatly I know to little about the ufc/ffc part of FEniCS to say > anything > useful about what it would take to implement, but I would like to here what > others think. > I vaguely recall a blueprint on identifying in the generated code global dofs. I think that this is necessary in order to handle parallel assembly, etc, of global dofs. Garth > Best regards, > > Johan > > _______________________________________________ > Mailing list: https://launchpad.net/~dolfin > Post to : [email protected] > Unsubscribe : https://launchpad.net/~dolfin > More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : [email protected] Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
