[petsc-users] Poor weak scaling when solving successive linear systems

[Smith, Barry F.]

  Please send the log file for 1000 with cg as the solver.

   You should make a bar chart of each event for the two cases to see which ones are taking more time and which are taking less (we cannot tell with the two logs you sent us since they are for different solvers.)

     

> On May 24, 2018, at 12:24 AM, Michael Becker <Michael.Becker at physik.uni-giessen.de> wrote:
> 
> I noticed that for every individual KSP iteration, six vector objects are created and destroyed (with CG, more with e.g. GMRES). 

   Hmm, it is certainly not intended at vectors be created and destroyed within each KSPSolve() could you please point us to the code that makes you think they are being created and destroyed?   We create all the work vectors at KSPSetUp() and destroy them in KSPReset() not during the solve. Not that this would be a measurable distance.



> This seems kind of wasteful, is this supposed to be like this? Is this even the reason for my problems? Apart from that, everything seems quite normal to me (but I'm not the expert here).
> 
> 
> Thanks in advance.
> 
> Michael
> 
> 
> 
> <log_view_125procs.txt><log_view_1000procs.txt>