interoperability with graphics (X, OpenGL, ...)

[ompiteam]

Stefan Eilemann would like more interoperability with graphics devices than just Cuda devices.

He uses things like 'XOpenDisplay(":0.") with OpenGL and needs a way to find the affinity and/or PCI device corresponding to a X server number and/or X xscreen. The bus ID is known to Xorg and may be in some xorg.conf but it's not easy to retrieve inside hwloc.

His terms:

• port: the X server number or unused (Windows/Mac)
• GL device: The X screen, affinity device (Windows) or CGL renderer ID (OS X)
• Cuda/OpenCL device

Cuda is already OK, but OpenCL seems to have nothing to help us.

Eyescale/Equalizer#57

[ompiteam]

Imported from trac issue 54. Created by bgoglin on 2011-11-30T03:52:49, last modified: 2013-03-06T07:33:50

[ompiteam]

Trac comment by eile on 2011-11-30 04:48:42:

nvidia-settings can query all this information (see GPU panel). Afaik it uses the NV-Control extension.

[ompiteam]

Trac comment by bgoglin on 2011-11-30 04:54:30:

Do you want something nvidia specific ou do you want something for any OpenCL or OpenGL device ?

[ompiteam]

Trac comment by eile on 2011-11-30 05:00:58:

nVidia-specific is good enough since it is available now. I would guess there is a similar extension from AMD.

In an ideal world I want something generic, but by the time we get the XOrg guys to support this and have all distributions updated it will be too late.

[ompiteam]

Trac comment by eile on 2011-11-30 06:05:06:

Sorry - wrong bug :(

[ompiteam]

Trac comment by bgoglin on 2012-03-18 17:22:45:

Looks like the NVIDIA-specific part of this is being worked on at
https://github.com/marwan-abdellah/HWLOC
I talked to the author, he's willing to contribute some code to hwloc.
Brice

[ompiteam]

Trac comment by bgoglin on 2013-03-06 07:33:50:

(In [5358]) Merge the GL branch into trunk

I am not merging with svn merge because the history is horrible.

This adds GPU OS devices such as ":0.0" for each NVIDIA display,
using the NVIDIA X-CONTROL X11 extension through the NVCtrl library.
It may later be extended to windows with WGL_NV_gpu_affinity and
WGL_AMD_gpu_association, or to OS X with CGL renderer IDs.
(that's why it's called GL and not just X11 display).

We also have a hwloc/gl.h to convert between :X.Y (string or pair)
and OS device objects.

This commit fixes #54.

Thanks to Marwan Abdellah and Stefan Eilemann (Blue Brain Project, EPFL)
for requesting, writing and testing some code.