[petsc-users] Slepc JD and GD converge to wrong eigenpair

[Matthew Knepley]

On Thu, Mar 30, 2017 at 3:05 AM, Jose E. Roman <jroman at dsic.upv.es> wrote:

>
> > El 30 mar 2017, a las 9:27, Toon Weyens <toon.weyens at gmail.com>
> escribió:
> >
> > Hi, thanks for the answer.
> >
> > I use MUMPS as a PC. The options -ksp_converged_reason,
> -ksp_monitor_true_residual and -ksp_view  are not used.
> >
> > The difference between the log_view outputs of running a simple solution
> with 1, 2, 3 or 4 MPI procs is attached (debug version).
> >
> > I can see that with 2 procs it takes about 22 seconds, versus 7 seconds
> for 1 proc. For 3 and 4 the situation is worse: 29 and 37 seconds.
> >
> > Looks like the difference is mainly in the BVmult and especially in the
> BVorthogonalize routines:
> >
> > BVmult takes 1, 6.5, 10 or even a whopping 17 seconds for the different
> number of proceses
> > BVorthogonalize takes 1, 4, 6, 10.
> >
> > Calculating the preconditioner does not take more time for different
> number of proceses, and applying it only slightly increases. So it cannot
> be mumps' fault...
> >
> > Does this makes sense? Is there any way to improve this?
> >
> > Thanks!
>
> Cannot trust performance data in a debug build:
>

Yes, you should definitely make another build configured using
--with-debugging=no.

What do you get for STREAMS on this machine

  make streams NP=4

>From this data, it looks like you have already saturated the bandwidth at 2
procs.

  Thanks,

    Matt


>
>       ##########################################################
>       #                                                        #
>       #                          WARNING!!!                    #
>       #                                                        #
>       #   This code was compiled with a debugging option,      #
>       #   To get timing results run ./configure                #
>       #   using --with-debugging=no, the performance will      #
>       #   be generally two or three times faster.              #
>       #                                                        #
>       ##########################################################
>
>
>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20170330/7f630b2c/attachment.html>