Hello,
I followed the suggestion in PETSc previous threads by adding options -pc_type asm -sub_pc_type lu Now the solver is really fast!!!!! Thanks you Jarunan Quoting Barry Smith <bsmith at mcs.anl.gov>: > > On Oct 20, 2009, at 9:52 AM, jarunan at ascomp.ch wrote: > >> Hello, >> >> I would like to know some information about GMRES performance in >> PETSc if you have any experience. >> >> I am running a parallel test case(9300 cells) comparing cpu time >> using by solvers in Petsc. While BICGSTAB was doing 0.9 sec, GMRES >> 15 sec with the same preconditioner(Additive Schwarz). I did not >> expect that GMRES would be that much slower. Everything is default. > > You need much more information than runtimes of the two cases to > understand why one is faster than the other. >> >> Please share your experiences, how the performance of solvers are >> in your test cases. Which option I should set to improve GMRES >> performance? Is there the best combination of Preconditioner and >> solver? > > Run both (with debugging turned off, hence optimized) using the > option -log_summary and look at where each is code is spending its > time. You can also see how many iterations (MatMult) each solver is > requiring. Feel free to send the -log_summary output to > petsc-maint at mcs.anl.gov if you do not understand it. > > Barry > >> >> Thank you very much >> Jarunan >> >> -- >> Jarunan Panyasantisuk >> Development Engineer >> ASCOMP GmbH, Technoparkstr. 1 >> CH-8005 Zurich, Switzerland >> Phone : +41 44 445 4072 >> Fax : +41 44 445 4075 >> E-mail: jarunan at ascomp.ch >> www.ascomp.ch -- Jarunan Panyasantisuk Development Engineer ASCOMP GmbH, Technoparkstr. 1 CH-8005 Zurich, Switzerland Phone : +41 44 445 4072 Fax : +41 44 445 4075 E-mail: jarunan at ascomp.ch www.ascomp.ch
