[Paraview] Bug 10274

[Utkarsh Ayachit]

FYI, I've made this a setting on the filter and made it off by
default. The next step would be to expose it as a GUI level setting
for the user to enable/disable as needed.

Utkarsh

On Mon, Feb 15, 2010 at 4:54 PM, burlen <burlen.loring at gmail.com> wrote:
> I noticed this bug report up on Mantis.
> http://www.paraview.org/Bug/view.php?id=10274
> I feel kind of responsible for this since I suggested geometry compression
> should be investigated.
>
> Just to clarify: The investigation I made
> (http://www.paraview.org/Bug/file_download.php?file_id=2866&type=bug) showed
> at most a 2x speed up, and only for very large data and slower networks. If
> you are going to implement geometry compression then there are a couple of
> things to keep in mind:
>
> 1) geometry compression hurts performance on fast networks
> 2) only makes much of a difference (and at most 2x speedup) on slower
> networks for very large data
> 3) for binary floating point data, zlib compression level affects run time
> drastically, but higher levels don't increase the compression ratio.
>
> I noticed that in vtkMPIMoveData the compression ratio is set by the compile
> time variable Z_DEFAULT_COMPRESSION, which is typically 6, that will kill
> any hopes of a speedup. You should always use zlib compression level of 1 on
> the binary floating point data.
>
> Also, if you're going to compress geometry or other binary floating point
> data during communication you might look at LZO
> http://www.oberhumer.com/opensource/lzo/
> I didn't do any benchmarks with LZO but they claim it's faster than zlib.
>
>
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