Hi Prof. Wolfgang,
Many thanks! Originally, I suspected that when solving two linear systems simultaneously by two threads would reduce time. But now it seems that this idea increases the complexity of communication between MPI communicators and coding, and also not surely to decrease computing time. I’m not going to try this idea at present. When I’m free, I will test its feasibility and post here the result. Thank you very much! All my best wishes, Jack 在 2017年5月24日星期三 UTC+8上午1:59:17，Wolfgang Bangerth写道： > > > Jack, > > > “The way to do this is to clone the MPI communicator you use for your > > overall > > problem once for each linear system. ” > > > > That means for my problem I have to copy the Vector and Matrix of one > > linear system（either the thermal diffusion or stokes flow） to another > > Vector and Matrix which are built with a clone of present communicator > > before starting a thread to solve this linear system. > > > > And then I have to copy the solution of this linear system to the > > targeted Vector which is built using the present MPI communicator for > > assembling systems. > > That seems too complicated. Just set up the linear system (=matrix, > vectors) with a different communicator from the beginning. > > > > By the way is it possible to copy Vector and Matrix of TrilinosWrappers > > to another ones those are initialized with another MPI communicator? > > I don't remember. It is certainly nor a usual operation. You'll have to > investigate whether copying also copies the communicator or not by > looking at the actual source. > > It is not common to solve linear systems on different threads in > parallel when using MPI. I don't want to say that that is not a good > idea -- it seems like a good idea for sure because it can hide some of > the latency associated with MPI communication, but it is not usually > done. I suspect that you will not save much time compared to just > solving the two linear systems one after the other. > > Best > W. > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: bang...@colostate.edu > <javascript:> > www: http://www.math.colostate.edu/~bangerth/ > -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
