warn message in log summary

[Lisandro Dalcin]

I even get consistent time deltas using 'gettimeofday' on my box!!
Perhaps PETSc has some bug somewere?? What do you think??

On 11/26/07, Richard Tran Mills <rmills at ornl.gov> wrote:
> Lisandro,
>
> Unfortunately, I see the same negative timings problem on the Cray XT3/4
> systems when I configure PETSc to use MPI_Wtime() for all its timings.  So
> that doesn't necessarily fix anything...
>
> --Richard
>
> Lisandro Dalcin wrote:
>
> > Perhaps PETSc should use MPI_Wtime as default timer. If a better one
> > is available, then use it. But then MPIUNI have to also provide an
> > useful, default implementation.
> >
> > Runing a simple test, like this (MPICH2):
> >
> > int main(void)
> > {
> >   int i;
> >   double t0[100],t1[100];
> >   MPI_Init(0,0);
> >   for (i=0; i<100; i++) {
> >     t0[i] = MPI_Wtime();
> >     t1[i] = MPI_Wtime();
> >   }
> >   for (i=0; i< 100; i++) {
> >     printf("t0=%e, t1=%e, dt=%e\n",t0[i],t1[i],t1[i]-t0[i]);
> >   }
> >   MPI_Finalize();
> >   return 0;
> > }
> >
> > and in the SAME box I get the PETSc warning, it consistently gives me
> > positive time deltas of the order of MPI_Wtick()...
>
>


-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594