Satish, Logs attached...hope they help.
Thanks, Tim. Satish Balay wrote: > Can you send the -log_summary for your runs [say p=1, p=8] > > Satish > > On Tue, 20 Nov 2007, Tim Stitt wrote: > > >> Hi all (again), >> >> I finally got some data back from the KSP PETSc code that I put together to >> solve this sparse inverse matrix problem I was looking into. Ideally I am >> aiming for a O(N) (time complexity) approach to getting the first 'k' columns >> of the inverse of a sparse matrix. >> >> To recap the method: I have my solver which uses KSPSolve in a loop that >> iterates over the first k columns of an identity matrix B and computes the >> corresponding x vector. >> >> I am just a bit curious about some of the timings I am obtaining...which I >> hope someone can explain. Here are the timings I obtained for a global sparse >> matrix (4704 x 4704) and solving for the first 1176 columns in the identity >> using P processes (processors) on our cluster. >> >> (Timings are given in seconds for each process performing work in the loop >> and >> were obtained by encapsulating the loop with the cpu_time() Fortran >> intrinsic. >> The MUMPS package was requested for factorisation/solving, although similar >> timings were obtained for both the native solver and SUPERLU) >> >> P=1 [30.92] >> P=2 [15.47, 15.54] >> P=4 [4.68, 5.49, 4.67, 5.07] >> P=8 [2.36, 4,23, 2.81, 2.54, 3.42, 2.22, 1.41, 3.15] >> P=16 [1.04, 0.45, 1.08, 0.27, 0.87, 0.93, 1.1, 1.06, 0.29, 0.34, 0.73, 0.25, >> 0.43, 1.09, 1.08, 1.1] >> >> Firstly, I notice very good scalability up to 16 processes...is this expected >> (by those people who use these solvers regularly)? >> >> Also I notice that the timings per process vary as we scale up. Is this a >> load-balancing problem related to more non-zero values being on a given >> processor than others? Once again is this expected? >> >> Please excuse my ignorance of matters relating to these solvers and their >> operation...as it really isn't my field of expertise. >> >> Regards, >> >> Tim. >> >> >> > > -- Dr. Timothy Stitt <timothy_dot_stitt_at_ichec.ie> HPC Application Consultant - ICHEC (www.ichec.ie) Dublin Institute for Advanced Studies 5 Merrion Square - Dublin 2 - Ireland +353-1-6621333 (tel) / +353-1-6621477 (fax) -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: log.1 URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20071120/6325b7c9/attachment.diff> -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: log.8 URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20071120/6325b7c9/attachment-0001.diff>
