This is what I was thinking of: *Parallel Hierarchical Visualization of Large Time-varying 3D Vector Fields* *Hongfeng Yu, Chaoli Wang, Kwan-Liu Ma
*David E DeMarle Kitware, Inc. R&D Engineer 28 Corporate Drive Clifton Park, NY 12065-8662 Phone: 518-371-3971 x109 On Tue, Aug 25, 2009 at 9:46 AM, David E DeMarle <[email protected]>wrote: > There was a paper at Super Computing last year (or maybe the year before) > about improved partitioning for stream tracing that would probably help > alot. Think of making a filter like D3 which moves data around to > repartition, such that the partitions take into account the principle flow > directions. That way particles stay resident much more often. The upfront > cost might be high to do the repartition, but afterwards stream tracing > would be faster. > > David E DeMarle > Kitware, Inc. > R&D Engineer > 28 Corporate Drive > Clifton Park, NY 12065-8662 > Phone: 518-371-3971 x109 > > > On Tue, Aug 25, 2009 at 4:42 AM, John Biddiscombe <[email protected]>wrote: > >> Burlen >> >> I have had performance issues with the Distributed Stream tracer, but in >> fact I found that in general, the problem of it not being very well >> optimized for parallel operation was not the main trouble. If you are using >> Unstructured Grids, and they are large (in my case 20million cells in a >> block), then the main time was taken by the building of cell links which are >> used to FindCEll inwhich an integration point lies. I modified the stream >> tracer interpolation to use a BSP tree (or CellLocator) and found a huge >> improvement in execution time. (minutes instead of hours). >> >> Secondly. the parallelization of the stream tracer is an inherent problem. >> One cannot integrate the streamline in block 2, until it has reached a >> boundary in block 1 - one must wait until the streamling traverses one block >> before passing it to the next. In actuality, the implementation could be >> improved with more intelligent seeding and rending/receiving of streamline >> seeds etc between iterations. >> >> The Particle tracer code could be modifed to produce streamlines in a >> serial or distributed manner and ought to give a 'reasonably' optimal >> solution to the problem - but in fact the chaps at kitware are at the moment >> (they tell me) in the process of revamping the streamline code to make use >> of CellLocators - and for this reason I recently committed my BSP tree code. >> >> Here's how to check your bottleneck. >> Find a large StructuredGrid dataset which is loaded in parallel. Generate >> streamlines. Time it. Convert the grdi to UnstructuredGrid and do the same. >> If test 1 takes 1 minute and test 2 1 hour, then it isn't the parallization >> that's the real issue, but the grid being used. >> >> JB >> >> >> >> >> >> We've been using the distributed stream tracer to generate 100s-1000s of >>> stream lines per time step. It's very slow, and it doesn't scale at all. >>> The class comments say as much. I'm sure there is a reason why this >>> implementation was chosen. Is there something that generally prevents real >>> parallel implementation? Is there a better implementation available out >>> there? >>> >>> There is this post a while back >>> http://www.paraview.org/pipermail/paraview/2009-July/012959.html >>> >>> What's the status? >>> >>> Thanks >>> Burlen >>> >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> Powered by www.kitware.com >>> >>> Visit other Kitware open-source projects at >>> http://www.kitware.com/opensource/opensource.html >>> >>> Please keep messages on-topic and check the ParaView Wiki at: >>> http://paraview.org/Wiki/ParaView >>> >>> Follow this link to subscribe/unsubscribe: >>> http://www.paraview.org/mailman/listinfo/paraview >>> >> >> >> -- >> John Biddiscombe, email:biddisco @ cscs.ch >> http://www.cscs.ch/ >> CSCS, Swiss National Supercomputing Centre | Tel: +41 (91) 610.82.07 >> Via Cantonale, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82 >> >> >> _______________________________________________ >> Powered by www.kitware.com >> >> Visit other Kitware open-source projects at >> http://www.kitware.com/opensource/opensource.html >> >> Please keep messages on-topic and check the ParaView Wiki at: >> http://paraview.org/Wiki/ParaView >> >> Follow this link to subscribe/unsubscribe: >> http://www.paraview.org/mailman/listinfo/paraview >> > >
_______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the ParaView Wiki at: http://paraview.org/Wiki/ParaView Follow this link to subscribe/unsubscribe: http://www.paraview.org/mailman/listinfo/paraview
