[vtkusers] Large performance difference between vtkResampleWithDataSet in VTK 8.1.0 and Resample with Dataset filter in Paraview 5.5

[Sujin Philip]

Hi Evan,

As Shawn mentioned it could be due to lack of multi-threading. Could you
provide us the configuration of the system you are using? Like the number
of cores/threads and the CPU frequency? Also please share the actual time
that ParaView and VTK are taking. Is it possible for you to try out a
slightly older VTK version and see if the performance difference is still
there?

Which dataset are you setting as input and which as source? The names are
unfortunately opposite between VTK-m and ParaView due to legacy reasons.
Probing with the unstructured grid as the source is much slower than
probing with the structured grid as the source. So please confirm that the
VTK pipeline is set up properly.

Please let me know if none these seem to be the cause of your problem and I
will dig deeper.

Thanks
Sujin



On Tue, May 15, 2018 at 9:52 AM, Shawn Waldon <shawn.waldon at kitware.com>
wrote:

> Hi Evan,
>
> I suspect the differece is that the ParaView binaries were compiled with
> TBB multithreading support and the Anaconda VTK was not.
> vtkResampleWithDataSet is set up to use TBB multithreading if available.
> Check the utilization of the cores on your computer when running each and
> you will see ParaView using all available cores and Anaconda's VTK probably
> only using one.  It is also possible the cell locator change improved
> things further but I'm not familiar with that.
>
> HTH,
>
> Shawn
>
> On Mon, May 14, 2018 at 7:54 PM, Evan Kao <tossin at gmail.com> wrote:
>
>> Hello all,
>>
>> I am trying to resample a structured grid data (~1.4M points, 1.3M cells)
>> with an unstructured grid (~320K points, 480K cells).  In Paraview 5.5,
>> this resampling is nearly instant with the Resample With Dataset filter.
>> Yet in a Python script using vtkResampleWithDataSet from VTK 8.1.0, the
>> same operation takes about 15 minutes (>2 orders of magnitude difference in
>> speed).  As far as I can tell from the VTK repository on Gitlab, the only
>> difference between the Paraview/release version and the 8.1.0 or 8.1.1
>> tagged releases is a switch in the cell locator.  Is this enough to explain
>> the difference in the performance?  If not, could someone enlighten me as
>> to what the possible factors are here?
>>
>> Also, if it matters, this is all on a Windows 7 64-bit machine.  Paraview
>> is installed from binaries, while VTK was downloaded from an Anaconda
>> distribution compiled by a third party.
>>
>> Thanks for your time,
>> Evan Kao
>>
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