[Paraview] PV & multiple video cards

[Berk Geveci]

By the way, if we wanted to go all the way on this, we would also
support Windows. I was told that there is an nvidia-specific function
that controls the GPU a context uses. I believe that it is this:

http://developer.download.nvidia.com/opengl/specs/WGL_nv_gpu_affinity.txt

I have no idea if ATI supports this.

-berk


On Tue, Jun 22, 2010 at 4:16 PM, Moreland, Kenneth <kmorel at sandia.gov> wrote:
> I think this is a good suggestion.  I don’t think the fact that it relies on
> processes being assigned in a particular order is a big deal.  The default
> allocation is usually to place contiguous ranks in the same node anyway.
>  The tiled display options also have heavy reliance on the order in which
> processes are assigned, and I don’t recall complaints about that.
>
> The only change I would suggest is to not have an option named
> --number-of-gpu-per-host change the display parameter.  The option name
> should reflect the fact that it is going to override the display environment
> variable.  Offhand, I cannot think of a single option name that reflects
> both the fact that you are changing the display and providing the number of
> screen ids to use.  Perhaps you would have two options, the
> --number-of-gpu-per-host as you described and a something like
> --set-display-server-id-by-process-id.  Since one does not make sense
> without the other, you could give an error if one is used independently.
>
> -Ken
>
>
> On 6/22/10 12:31 PM, "burlen" <burlen.loring at gmail.com> wrote:
>
> Hi,
>
> I realized that my suggestion relies on processes being assigned in a
> particular order. So something slightly more complicated would need to
> be done to determine the number of processes running on each host. Still
> it would be pretty simple way to make folks lives easier. Let me know
> what you think.
>
> Burlen
>
> burlen wrote:
>> Hi,
>>
>> currently we suggest users rely on details particular to specific MPI
>> implementations
>>
>> (http://paraview.org/Wiki/Setting_up_a_ParaView_Server#Multiple_GPUs_Per_Node)
>> to set up PV server on clusters with multiple graphics cards per node.
>> It seems to me that this reliance on non standard implementation
>> details isn't necessary for the most common case and it can introduce
>> some complication to get PV running on various installations.
>>
>> There is something simple that we could do to make users life easier.
>> ParaView could handle a common configuration of multiple graphics
>> cards seamlessly with very little effort via an additional command
>> line option.
>>
>> Two common ways to address multiple video devices in X11 via the
>> DISPLAY variable are, 1) by server id (":[server].0") or 2) by screen
>> id (":0.[screen]").  It depends on how X11 is setup, but I think the
>> latter is the most common.
>>
>> If the user were to tell PV how many video devices are available on
>> each node via the following command line variable, PV could assign
>> rendering contexts cyclically across the available devices by setting
>> the DISPLAY variable for the user.
>>
>> --number-of-gpu-per-host=N
>>
>> as each server starts he will make the computation to set the DISPLAY
>> variable so that render contexts are cycled across the available devices.
>>
>> For example, something like the folowing could be added to
>> Filters/vtkPVMain.cxx
>>
>> if (numGpuPerHost)
>>  {
>>  int screenId=LocalProcId%numGpuPerHost
>>  setenv("DISPALY=:0.%i",screenId)
>>  }
>>
>> This would conflict with the "-display" option, if both are present PV
>> would exit and print some error message.
>>
>> Do you guys think this would be a reasonable approach to handle a
>> common use case?
>> Burlen
>>
>
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>    ****      Kenneth Moreland
>     ***      Sandia National Laboratories
> ***********
> *** *** ***  email: kmorel at sandia.gov
> **  ***  **  phone: (505) 844-8919
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