Re: [Libmesh-users] problems solving ex8 in parallel

[John P. <pet...@cf...>]

Hi,

I recently checked in code to the Mesh partitioners to set
the processor IDs of the nodes.  Are you working with the
CVS libmesh?  65536 is just a default which means 'not set'.

-John


Ingo Schmidt writes:
 > My idea is to check the processor ID
 > ((mesh.node(res_node_no-1)).processor_id()) of the result node and
 > compare it with libMesh::processor_id() before writing the nodal data to
 > the output file (using the previous version of ex8).
 > Stupidly the processor ID of the node is 65536. Does libMesh actually
 > assign the proc ID to the DofObject?
 > 
 > regards
 > 
 > Ingo
 > 
 > Ingo Schmidt schrieb:
 > > Hi,
 > >
 > > at first I was glad that the bug fix is working (i.e. compiling and
 > > running the code in parallel) but yesterday I checked the benefit of
 > > parallelisation.
 > > The benefit is unfortunately is an impairment. Increasing the number of
 > > CPU's slows down the computation time in a considerable measure.
 > > E.g.
 > > example 8:    1 CPU approx. 9 seconds
 > >                       2 CPU's approx. 14 seconds
 > >
 > > That's pretty bad...
 > >
 > > best regards
 > >
 > > Ingo
 > >
 > > Roy Stogner schrieb:
 > >   
 > >> On Mon, 19 Mar 2007, Roy Stogner wrote:
 > >>
 > >>     
 > >>> I'll commit a fix to CVS this afternoon, but hopefully that's enough
 > >>> info to get your own code back on track.
 > >>>       
 > >> I may not be familiar enough with MPI or our NumericVector API, but I
 > >> don't actually see how to write an efficient, simple fix.  So, I've
 > >> committed an inefficient and convoluted fix to CVS instead.
 > >>
 > >> I'll also see about making it more convenient to run these examples in
 > >> parallel; I can't believe that nobody has ever run ex8 in parallel
 > >> under METHOD=dbg before.  My application Makefiles use a LIBMESHRUN
 > >> environment variable to find my own "mpirun -whatever" invocation, and
 > >> a LIBMESHOPTIONS environment variable to hold extra PETSc options to
 > >> be added to the end of commands; if there aren't any objections, I'll
 > >> make the example Makefiles check the same variables, so there will be
 > >> at least one person regularly trying "make run_examples" in parallel.
 > >> ---
 > >> Roy
 > >>     
 > >
 > >   
 > 
 > -- 
 > Dipl.-Ing. Ingo Schmidt
 > Institute of Modelling and Computation
 > 
 > Hamburg University of Technology	tel: +49/(0)40/42878-4483
 > Denickestr.17				fax: +49/(0)40/42878-4353	
 > Building L/ room: 3032			e-mail: ingo.schmidt@TUHH.de
 > 21075 Hamburg
 > 
 > http://www.mub.TU-Harburg.de
 >