[Paraview] Is there any point to compiling with MPI but without offscreen rendering?

[Burlen Loring]

Hi Rich,

You're always going to want to build with MPI when running on a cluster. 
Leveraging your cluster's graphics cards comes down to building with or 
without os mesa. you probably want to provide both builds, and select 
the build to run depending on whether the user has requested nodes that 
contain graphics cards or not. Hardware accelerated rendering can be 
faster than software based rendering depending on the amount of 
contention there is for the graphics card. eg 16 mpi ranks hitting the 
same card will likely be slower than 16 cpu cores running os mesa. When 
submitting a job you could always control this by limiting the number of 
mpi ranks per graphics card. Also, some rendering algorithms, such as 
surface LIC, are disabled when using os mesa. it's nice to have the 
hardware accelerated build in order to access the other algorithms when 
you need them.

Burlen

On 10/1/2012 5:05 PM, Cook, Rich wrote:
> We have large clusters and some of them have graphics cards on them.  Most don't.  So normally I expect to be using -DVTK_USE_OFFSCREEN:BOOL=ON   -DPARAVIEW_USE_MPI:BOOL=ON with cmake.
> I got to thinking.  First, if I compile with -DVTK_USE_OFFSCREEN:BOOL=ON then why do I have to use --use-offscreen-rendering to launch the pvservers.  Secondly, can pvservers render to graphics cards for distributed rendering under MPI?  If so, does it make sense to do -DVTK_USE_OFFSCREEN:BOOL=OFF   -DPARAVIEW_USE_MPI:BOOL=ON ??
>