Shidi, Rethink the comm passed to your ISCreateGeneral(). Could you do it with PETSC_COMM_SELF?
--Junchao Zhang On Sun, Jul 5, 2020 at 3:27 PM Mark Adams <mfad...@lbl.gov> wrote: > The column after the time in the PETSC output, on the ISCreateGeneral > row, with -log_view, shows the ratio of the max time (shown) to min time. > If you are using your own timers just report the min and max time that you > measure. > You can also put an MPI_Barrier before the call to ISCreateGeneral to get > clean data. > And I trust that the problem is well load balance, that is, all processors > have the same amount of data. > > On Sun, Jul 5, 2020 at 4:00 PM Y. Shidi <ys...@cam.ac.uk> wrote: > >> Thank you for your reply Mark. >> What do you mean by ratio (max/min)? >> Do I need to turn on some options for this? >> >> Kind regards, >> Shidi >> >> On 2020-07-05 20:15, Mark Adams wrote: >> > ISCreateGeneral just takes your indices and caches them. But it is a >> > synch point. What ratio (max/min) is PETSc reporting in this data? >> > >> > On Sun, Jul 5, 2020 at 1:51 PM Y. Shidi <ys...@cam.ac.uk> wrote: >> > >> >> Dear developers, >> >> >> >> I am currently doing a weak scaling test, and find that >> >> the weak scaling results for ISCreateGeneral() is very bad. >> >> For 2, 4, 8 processors, the running times for completing >> >> ISCreateGeneral() are: >> >> 0.687494, 3.00597 and 10.0613. >> >> I am not sure if this is normal. >> >> >> >> Thank you for your time. >> >> >> >> Kind Regards, >> >> Shidi >> >
