Hello again, I am using v3.1 of PETSc.
I changed the grid sizes slightly and I'm including 4 log_summary files. The times are shown below. I have not modified the example at all except in specifying the matrix size. Could it be that I need much larger? When I tried much larger matrices I think I might have got an error because I was using too much memory. n time 2 22s 4 29.8s 8 33.7s 16 28.3s Sorry for my first email but I hope this has more information. Cheers, Francis > On 2012-02-23, at 3:27 PM, Jed Brown wrote: > Always send output with -log_summary for each run that you do. > On Thu, Feb 23, 2012 at 14:16, Francis Poulin <fpoulin at uwaterloo.ca> wrote: > Hello, > > I am learning to use PetSc but am just a notice. I have a rather basic > question to ask and couldn't not find it on the achieves. > > I am wanting to test the scalability of a Multigrid solver to the 3D Poisson > equation. I found ksp/ex22.c that seems to solve the problem that I'm > interested in. I ran it on a large server using different processors. > > The syntax that I use to run using MPI was > > ./ex22 -da_grid_x 64 -da_grid_y 64 -da_grid_z 32 > > Which version of PETSc? > > > I tested it using 2, 4, 8, 16 cpus and found that the time increases. See > below. Clearly there is something that I don't understand since the time > should be reduced. > > n wtime > --------------------- > 2 3m58s > 4 3m54s > 8 5m51s > 16 7m23s > > Any advice would be greatly appreciated. > > Best regrads, > Francis > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0005.htm> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: saw_log_summary_n2.txt URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0004.txt> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0006.htm> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: saw_log_summary_n4.txt URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0005.txt> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0007.htm> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: saw_log_summary_n8.txt URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0006.txt> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0008.htm> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: saw_log_summary_n16.txt URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0007.txt> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120223/79002856/attachment-0009.htm>
