[petsc-users] -log_summary for MatMult

[Alexander Grayver]

Matt,

According to that code:

486:*PetscErrorCode  MatMult_MPIDense(Mat  mat,Vec  xx,Vec  yy)*
487:{
488:   Mat_MPIDense   *mdn = (Mat_MPIDense*)mat->data;

492:  VecScatterBegin(mdn->Mvctx,xx,mdn->lvec,INSERT_VALUES,SCATTER_FORWARD);
493:   VecScatterEnd(mdn->Mvctx,xx,mdn->lvec,INSERT_VALUES,SCATTER_FORWARD);
494:   MatMult_SeqDense(mdn->A,mdn->lvec,yy);
495:   return(0);
496:}


Each process has its own local copy of the whole vector vectors?

On 15.06.2012 14:27, Matthew Knepley wrote:
> On Fri, Jun 15, 2012 at 8:22 PM, Alexander Grayver 
> <agrayver at gfz-potsdam.de <mailto:agrayver at gfz-potsdam.de>> wrote:
>
>     Hello,
>
>     When I call MatMult with MPIDENSE matrix in log summary I see:
>
>     Event                Count      Time (sec)     Flops              
>                   --- Global ---  --- Stage ---   Total
>                       Max Ratio  Max     Ratio   Max  Ratio  Mess  
>     Avg len Reduct  %T %f %M %L %R  %T %f %M %L %R Mflop/s
>     ------------------------------------------------------------------------------------------------------------------------
>     MatMult                1 1.0 9.5740e-01 1.5 8.19e+08 1.0 0.0e+00
>     0.0e+00 1.0e+00  2 40  0  0  5   2 40  0  0  6  3419
>     MatMultTranspose       1 1.0 1.0793e+00 1.4 8.18e+08 1.0 0.0e+00
>     0.0e+00 2.0e+00  2 40  0  0 11   2 40  0  0 11  3030
>
>
>     Why do number of messages and their length equal zero?
>
>
> Because it uses only collectives.
>
>    MAtt
>
>
>     -- 
>     Regards,
>     Alexander
>
>
>
>
> -- 
> 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


-- 
Regards,
Alexander

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