[petsc-users] timer in PETSc

[Fande Kong]

Thanks. I did add my several events. From the following cases, we possibly
can find an explanation.

(1)

Summary of Stages:   ----- Time ------  ----- Flops -----  --- Messages ---
-- Message Lengths --  -- Reductions --

                        Avg     %Total     Avg     %Total   counts   %Total
    Avg         %Total   counts   %Total

 0:      Main Stage: 1.2115e+03  91.0%  8.6211e+12   2.3%  5.937e+07
3.2%  7.314e+03       77.2%  2.344e+03  10.1%

 1:        MG Apply: 1.1994e+02   9.0%  3.6819e+14  97.7%  1.780e+09
96.8%  2.160e+03       22.8%  2.080e+04  89.9%

(2)    Summary of Stages:   ----- Time ------  ----- Flops -----  ---
Messages ---  -- Message Lengths --  -- Reductions --

                        Avg     %Total     Avg     %Total   counts   %Total
    Avg         %Total   counts   %Total

 0:      Main Stage: 9.9736e+02  47.6%  2.4648e+13   0.8%  5.813e+07
1.0%  1.013e+03       32.5%  3.151e+03   2.7%

 1:        MG Apply: 1.0959e+03  52.4%  2.9005e+15  99.2%  5.734e+09
99.0%  2.102e+03       67.5%  1.114e+05  97.2%



In the fist case, we do not have any warnings and the second case produces
a warning. I am using MG as a preconditioner. When the MG is cheap like
case 1, the Main Stage time is larger than the MG stage. We do not have any
warnings. If the MG is expensive, the Main Stage time is smaller than MG.
We have a warning now because SNESSolve time is larger than Main Stage.
SNESSolve time includes outer solver and MG preconditioner.


Why we do not add MG time to the Main Stage. Should the Main Stage be the
total time?


Fande,

On Fri, Apr 10, 2015 at 2:30 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   Are you adding your own events or stages or just running with
> -log_summary?
>
>   If you added your own events or stages this likely happened because you
> changed between stages within an event so its start time is logged in one
> stage but the end time correct gets put into a different stage.
>
>   Barry
>
> > On Apr 10, 2015, at 3:22 PM, Fande Kong <fande.kong at colorado.edu> wrote:
> >
> > Hi all,
> >
> > I am running an application with more than 4,000 cores. I get a warning
> in the -log_summary: Warning -- total time of even greater than time of
> entire stage -- something is wrong with the timer.
> >
> > I have no any clues for this warning. Any suggestions to remove it?
> >
> > Thanks,
> >
> > Fande,
>
>
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