Can you try running the code with --implicit_neighbor_dofs on the command line? By default the matrix sparsity is computed assuming continuous shape functions, but for a DG forumation this is not a good assumption. Let me know if that works for you, if so we can look at putting something more sophisticated in the library to detect this situation and handling it automatically. -Ben
________________________________ From: [EMAIL PROTECTED] on behalf of Roy Stogner Sent: Sun 5/11/2008 10:31 PM To: luyi Cc: [email protected] Subject: Re: [Libmesh-users] about the long time for the assemble of first step! On Mon, 12 May 2008, luyi wrote: > Now I write a DG programme on libmesh, when I use the FIRST or higher > order basis, the first step is too slow, > besides this everything is ok, I use XYZ basis and I check the code by > perf_log, the time ratio is up to snuff. The first time step (especially in a non-adaptive run) has some overhead that later timesteps don't, but it's also possible you've found a bug. If we're not preallocating the sparse matrix with the correct sparsity pattern, for example, PETSc might take quite a long time on the first assembly. Could you run your code for only one time step and check the perf_log on that, to see what part of the code is taking too long? --- Roy ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
