From: John Stone (johns_at_ks.uiuc.edu)
Date: Fri Sep 26 2014 - 09:55:36 CDT

Spencer,
  The CUDA device list shown by VMD seems to be missing device [1],
what kind of GPU is device [1]? Can you email the output of "nvidia-smi"?

Most likely what's going on here is that you have a mix of GPU hardware
generations, and OptiX is trying to use all 5 of them, although [1] is
perhaps not usable for some reason. If so, you'll need to tell VMD not
to let OptiX try to use the problematic GPU, by setting the VMDOPTIXDEVICEMASK
environment variablle appropriately.

In C-shell you would do:
  setenv VMDOPTIXDEVICEMASK 0x1
in bourne/bash shell you would do
  VMDOPTIXDEVICEMASK=0x1
  export VMDOPTIXDEVICEMASK

The device mask represents binary bits associated with each GPU.
Here are some simple examples:

Use only device 0:
  setenv VMDOPTIXDEVICEMASK 0x1
Use devices 0, 1:
  setenv VMDOPTIXDEVICEMASK 0x3
Use devices 0, 2:
  setenv VMDOPTIXDEVICEMASK 0x5
Use devices 0, 2, 3, 4
  setenv VMDOPTIXDEVICEMASK 0x1d

The tricky part is that OptiX uses a different device numbering than
CUDA does, so you may have to fiddle with the mask to get it right.
I plan to add more VMD startup output to emit the OptiX device numbering
much like the CUDA code does, to make this process simpler.

Cheers,
  John Stone
  vmd_at_ks.uiuc.edu

On Fri, Sep 26, 2014 at 10:40:07AM -0400, Stober, Spencer T wrote:
> Hello,
>
>
>
> I am having issues using the new CUDA accelerated Tachyon renderer. Any
> help is much appreciated.
>
>
>
> I receive the following error when I attempt to render a scene using OptiX
> Tachyon:
>
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Info) Rendering current scene to 'vmdscene.ppm' ...
>
> ERROR) OptiX error: Invalid value (Details: Function "RTresult
> _rtContextSetDevices(RTcontext, unsigned int, const int*)" caught
> exception: The list of devices is incompatible., [1575404])
> (OptiXRenderer.C:505
>
> OptiX: An error occured validating the context. Rendering is aborted.
>
> Total OptiX rendering time: 0.2 sec
>
> Info) Executing post-render cmd 'display vmdscene.ppm' ...
>
> display: Improper image header `vmdscene.ppm' @ pnm.c/ReadPNMImage/297.
>
> Info) Rendering complete.
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>
> I believe my CUDA devices are recognized and configured properly (they
> work for NAMD), and this is the startup message I get when I start VMD:
>
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Info) VMD for LINUXAMD64, version 1.9.2beta1 (September 12, 2014)
>
> Info) http://www.ks.uiuc.edu/Research/vmd/
>
> Info) Email questions and bug reports to vmd_at_ks.uiuc.edu
>
> Info) Please include this reference in published work using VMD:
>
> Info) Humphrey, W., Dalke, A. and Schulten, K., `VMD - Visual
>
> Info) Molecular Dynamics', J. Molec. Graphics 1996, 14.1, 33-38.
>
> Info) -------------------------------------------------------------
>
> Info) Multithreading available, 16 CPUs detected.
>
> Info) Free system memory: 254232MB (98%)
>
> Info) Creating CUDA device pool and initializing hardware...
>
> Info) Ignoring CUDA-capable GPUs used for display
>
> Info) Detected 4 available CUDA accelerators:
>
> Info) [0] Tesla K20Xm 14 SM_3.5 @ 0.73 GHz, 5.6GB RAM, AE2, ZCP
>
> Info) [2] Tesla K20Xm 14 SM_3.5 @ 0.73 GHz, 5.6GB RAM, AE2, ZCP
>
> Info) [3] Tesla K20Xm 14 SM_3.5 @ 0.73 GHz, 5.6GB RAM, AE2, ZCP
>
> Info) [4] Tesla K20Xm 14 SM_3.5 @ 0.73 GHz, 5.6GB RAM, AE2, ZCP
>
> Info) Detected 5 available TachyonL/OptiX ray tracing accelerators
>
> Warning) Detected X11 'Composite' extension: if incorrect display occurs
>
> Warning) try disabling this X server option. Most OpenGL drivers
>
> Warning) disable stereoscopic display when 'Composite' is enabled.
>
> Info) OpenGL renderer: Quadro 2000D/PCIe/SSE2
>
> Info) Features: STENCIL MSAA(4) MDE CVA MTX NPOT PP PS GLSL(OVFGS)
>
> Info) Full GLSL rendering mode is available.
>
> Info) Textures: 2-D (16384x16384), 3-D (2048x2048x2048), Multitexture
> (4)
>
> Info) Dynamically loaded 2 plugins in directory:
>
> Info) /data/lib/vmd/plugins/LINUXAMD64/molfile
>
> after#0
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>
>
>
> Spencer T. Stober, Ph.D.
>
> ExxonMobil Research and Engineering
>
> 600 Billingsport Rd
>
> Paulsboro, NJ 08066
>
> Phone: 856-224-2638
>
> Email: [1]spencer.t.stober_at_exxonmobil.com
>
>
>
> References
>
> Visible links
> 1. mailto:spencer.t.stober_at_exxonmobil.com

-- 
NIH Center for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
http://www.ks.uiuc.edu/~johns/           Phone: 217-244-3349
http://www.ks.uiuc.edu/Research/vmd/