[petsc-users] Code speedup after upgrading

[Dave May]

Nice to hear!
The answer is simple, PETSc is awesome :)

Jokes aside, assuming both petsc builds were configured with
—with-debugging=0, I don’t think there is a definitive answer to your
question with the information you provided.

It could be as simple as one specific implementation you use was improved
between petsc releases. Not being an Ubuntu expert, the change might be
associated with using a different compiler, and or a more efficient BLAS
implementation (non threaded vs threaded). However I doubt this is the
origin of your 2x performance increase.

If you really want to understand where the performance improvement
originated from, you’d need to send to the email list the result of
-log_view from both the old and new versions, running the exact same
problem.

>From that info, we can see what implementations in PETSc are being used and
where the time reduction is occurring. Knowing that, it should be clearer
to provide an explanation for it.


Thanks,
Dave


On Tue 23. Mar 2021 at 06:24, Mohammad Gohardoust <gohardoust at gmail.com>
wrote:

> Hi,
>
> I am using a code which is based on petsc (and also parmetis). Recently I
> made the following changes and now the code is running about two times
> faster than before:
>
>    - Upgraded Ubuntu 18.04 to 20.04
>    - Upgraded petsc 3.13.4 to 3.14.5
>    - This time I installed parmetis and metis directly via petsc by
>    --download-parmetis --download-metis flags instead of installing them
>    separately and using --with-parmetis-include=... and
>    --with-parmetis-lib=... (the version of installed parmetis was 4.0.3 before)
>
> I was wondering what can possibly explain this speedup? Does anyone have
> any suggestions?
>
> Thanks,
> Mohammad
>
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