On Wed, Sep 29, 2010 at 14:51, Moinier, Pierre (UK)
<Pierre.Moinier at baesystems.com> wrote:
> Jed,
>
> The matrix is 1000000x1000000 and I have 4996000 non zeros

These statistics look like perhaps this matrix comes from a 5-point
discretization of an elliptic operator.  Is that true?

> Here is the output for a single proc:

You'll want to compare the time in each event when run in parallel:

> MatMult ? ? ? ? ? ? 1633 1.0 1.6247e+01 1.0 1.47e+10 1.0 0.0e+00 0.0e+00
> 0.0e+00 36 43 ?0 ?0 ?0 ?36 43 ?0 ?0 ?0 ? 904

16 seconds in this event, 904 Mflop/s is good for a problem like this
on a single core.

> VecDot ? ? ? ? ? ? ?3266 1.0 4.4834e+00 1.0 6.53e+09 1.0 0.0e+00 0.0e+00
> 0.0e+00 10 19 ?0 ?0 ?0 ?10 19 ?0 ?0 ?0 ?1457
> VecNorm ? ? ? ? ? ? 1634 1.0 1.2968e+01 1.0 3.27e+09 1.0 0.0e+00 0.0e+00
> 0.0e+00 28 10 ?0 ?0 ?0 ?28 10 ?0 ?0 ?0 ? 252

This is confusing, the norms should take about a tenth of this (they
should have almost double the Mflop/s of VecDot).  Is there something
else running on this machine?  Anyone have other ideas?

> VecAXPY ? ? ? ? ? ? 3266 1.0 5.5580e+00 1.0 6.53e+09 1.0 0.0e+00 0.0e+00
> 0.0e+00 12 19 ?0 ?0 ?0 ?12 19 ?0 ?0 ?0 ?1175
> VecAYPX ? ? ? ? ? ? 1632 1.0 2.5961e+00 1.0 3.26e+09 1.0 0.0e+00 0.0e+00
> 0.0e+00 ?6 10 ?0 ?0 ?0 ? 6 10 ?0 ?0 ?0 ?1257

These look normal.

> KSPSolve ? ? ? ? ? ? ? 1 1.0 4.4828e+01 1.0 3.43e+10 1.0 0.0e+00 0.0e+00
> 0.0e+00 98100 ?0 ?0 ?0 ?98100 ?0 ?0 ?0 ? 765

And here's your solve total, the aggregate numbers look fine.

Jed

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