[Paraview] Off Screen Rendering

[chew ping]

Dear all,

 

i'm doing parallel rendering using 2 machines (np4), i notice an obvious difference between using offscreen-rendering (faster) and without offscreen-rendering (much slower). i realize this from the timer log:

 

 

Case 1: with offscreen-rendering

----------------------------------------------------------

 

Local Process

Still Render, 0.666444 seconds

Execute vtkMPIMoveData id: 519, 0.000199 seconds

Execute vtkPolyDataMapper id: 311, 0.000106 seconds

　

 

Server, Process 0

Execute vtkFileSeriesReader id: 238, 0.645881 seconds

Execute vtkPVGeometryFilter id: 305, 0.005891 seconds

Execute vtkPVCacheKeeper id: 516, 7.8e-05 seconds

Execute vtkMPIMoveData id: 519, 0.000212 seconds

Execute vtkOrderedCompositeDistributor , 0.000152 seconds

Execute vtkPolyDataMapper id: 311, 0.000274 seconds

 

Server, Process 1

Execute vtkFileSeriesReader id: 238, 0.000275 seconds

Execute vtkPVGeometryFilter id: 305, 0.005299 seconds

Execute vtkPVCacheKeeper id: 516, 7.7e-05 seconds

Execute vtkMPIMoveData id: 519, 0.000147 seconds

Execute vtkOrderedCompositeDistributor , 0.000117 seconds

Execute vtkPolyDataMapper id: 311, 9.9e-05 seconds

 

Server, Process 2

Execute vtkFileSeriesReader id: 238, 0.000258 seconds

Execute vtkPVGeometryFilter id: 305, 0.004765 seconds

Execute vtkPVCacheKeeper id: 516, 7.7e-05 seconds

Execute vtkMPIMoveData id: 519, 0.000147 seconds

Execute vtkOrderedCompositeDistributor , 0.000111 seconds

Execute vtkPolyDataMapper id: 311, 9.5e-05 seconds

 

Server, Process 3

Execute vtkFileSeriesReader id: 238, 0.000352 seconds

Execute vtkPVGeometryFilter id: 305, 0.005351 seconds

Execute vtkPVCacheKeeper id: 516, 7.7e-05 seconds

Execute vtkMPIMoveData id: 519, 0.000168 seconds

Execute vtkOrderedCompositeDistributor , 0.000111 seconds

Execute vtkPolyDataMapper id: 311, 0.000108 seconds

 

---------------------------------------------------------------

 

 

 

Case 2: without offscreen-rendering

---------------------------------------------------------------

 

Local Process

Still Render, 4.86495 seconds

Execute vtkMPIMoveData id: 520, 2.81566 seconds

Execute vtkPolyDataMapper id: 312, 0.00012 seconds

Execute vtkPolyDataMapper id: 148, 7.6e-05 seconds　

　

 

Server, Process 0

Execute vtkFileSeriesReader id: 239, 0.659133 seconds

Execute vtkPVGeometryFilter id: 306, 0.026125 seconds

Execute vtkPVCacheKeeper id: 517, 7.8e-05 seconds

Execute vtkMPIMoveData id: 520, 2.53214 seconds

Dataserver gathering to 0, 1.98166 seconds

Dataserver sending to client, 0.549715 seconds

Execute vtkOrderedCompositeDistributor , 0.000175 seconds

 

Server, Process 1

Execute vtkFileSeriesReader id: 239, 0.000446 seconds

Execute vtkPVGeometryFilter id: 306, 0.026313 seconds

Execute vtkPVCacheKeeper id: 517, 7.3e-05 seconds

Execute vtkMPIMoveData id: 520, 0.232435 seconds

Dataserver gathering to 0, 0.232117 seconds

Execute vtkOrderedCompositeDistributor , 0.00012 seconds

 

Server, Process 2

Execute vtkFileSeriesReader id: 239, 0.000519 seconds

Execute vtkPVGeometryFilter id: 306, 0.026063 seconds

Execute vtkPVCacheKeeper id: 517, 7e-05 seconds

Execute vtkMPIMoveData id: 520, 1.31373 seconds

Dataserver gathering to 0, 1.31341 seconds

Execute vtkOrderedCompositeDistributor , 0.000119 seconds

 

Server, Process 3

Execute vtkFileSeriesReader id: 239, 0.000459 seconds

Execute vtkPVGeometryFilter id: 306, 0.004905 seconds

Execute vtkPVCacheKeeper id: 517, 6.9e-05 seconds

Execute vtkMPIMoveData id: 520, 0.764289 seconds

Dataserver gathering to 0, 0.740679 seconds

Execute vtkOrderedCompositeDistributor , 0.000136 seconds

 

--------------------------------------------------------------------

 

 

Unlike Case 2, Case 1 does not show any 'Dataserver gathering to 0' or 'Dataserver sending to client'

so i guess what makes Case 2 slower is because the vtkMPIMoveData is doing extra thing to move data amongst processes

 

btw, whenever i run it without -offscreen-rendering, i get this message:

"Display is not accessible on the server side. Remote rendering will be disabled."

 

based on what i read from paraview tutorial, what i understand is that the parallel rendering algorithm allows each process to independently render its partition of the geometry and then composites the partial images together to form the final image. Is this what happened in Case 2 because it has 'Dataserver gathering to 0' or 'Dataserver sending to client'?

 

actually what i dont understand is why case 2 is much slower than case 1? 

is it because different 'things' are going on in the processes when offscreen-rendering is on/off?

 

 

any help / reply is highly appreciated

 

Best Regards,

chewping

 

 

 

 

 

 

 

 

 

 

 
 		 	   		  
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