[petsc-users] AOCreateBasic is not scaling

[Matthew Knepley]

On Wed, Mar 2, 2011 at 4:25 PM, M. Scot Breitenfeld <brtnfld at uiuc.edu>wrote:

> Hi,
>
> First, thanks for the suggestion on using MPISBAIJ for my A matrix, it
> seems to have cut down on my memory and assembly time. For a 1.5 million
> dof problem:
>
>    # procs:                  2        4        8           16
> ----------------------------------------------------------------
> Assembly (sec):        245     124      63       86
> Solver (sec):              924     578     326     680
>
> Memory (GB):          2.5        1.4     .877    .565
>
> The problem I have is the amount of time it's taking in AOCreateBasic,
> it takes longer then assembling,
>
>    # procs:                            2        4        8         16
> ---------------------------------------------------------------------
> AOCreateBasic (sec):         .6      347      170     197
>
> Is there something that I can change or something I can look for that
> might be causing this increase in time as I go from 2 to 4 processors
> (at least it scales from 4 to 8 processors). I read in the archive that
> AOCreateBasic is not meant to be scalable so maybe there is nothing I
> can do.
>

Yes, this is non-scalable. What are you using it for?

   Matt


> Thanks,
> Scot
>
>
>
>
>
>
>


-- 
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
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