VMD-L Mailing List

From: Sabuj Pattanayek (sabuj.pattanayek_at_Vanderbilt.Edu)
Date: Tue Jan 04 2005 - 17:28:46 CST

Yup, running vmd 1.8.2 and hardware stereo is enabled in XF86Config
(Option "Stereo" "3"). What you said worked, that is the speed is normal
with the newer drivers and VMDPREFERSTEREO off and that the speed
becomes normal if VMDPREFERSTEREO is on and hardware stereo is enabled
(crystaleyes mode).

So would you suggest that I use the newer drivers where I have to turn
the variable on or off depending on whether I want stereo or v1.0.5336
where it doesn't seem to matter? I mean are there any performance or
features gained as far as visuals are concerned with the newer drivers
or does it not really make a difference in VMD?

Thanks for your help!

John Stone wrote:
> Sabuj,
> I assume you're running VMD 1.8.2? If not, let me know which version
> of VMD you're using and I can give more suggestions.
>
> I know that NVidia made a lot of changes that relate to the implementation
> of stereoscopic rendering on the Quadro cards. Even now with the most recent
> drivers, they have a particularly egregious performance issue that affects
> stereo rendering. If you have stereo enabled in your NVidia driver, and
> you're running VMD with the "VMDPREFERSTEREO" variable set, but you
> _don't_ have VMD displaying in stereo, there's a HUGE performance loss caused
> by the way their OpenGL driver implements glDrawBuffer(GL_BACK) when running
> in a stereoscopic visual. No other cards/drivers I've ever seen have this
> problem, and it's a huge speed hit. My understanding is that NVidia implements
> glDrawBuffer(GL_BACK) with a software-based pixel copy when you're running
> in a stereo mode but not rendering in stereo. When one calls
> glDrawBuffer(GL_BACK_LEFT) or glDrawBuffer(GL_BACK_RIGHT) the problem goes
> away and speed is normal (i.e. when you have the stereo mode in VMD
> set to CrystalEyes).
>
> All said however, this only affects you if you have the board running in
> a stereoscopic mode. Since you didn't say what video mode you're using,
> I'm not even certain any of this applies to you. A lot of people with
> Quadro cards buy them specifically so they can do stereo, so I thought
> I'd mention this particular issue so you're aware of it.
>
> The NVidia X config option for stereo is usually:
> Option "Stereo" "3"
>
> So if you see that in your config files, that may be related to your
> performance problem.
>
> John
>
> On Tue, Jan 04, 2005 at 04:06:39PM -0600, Sabuj Pattanayek wrote:
>
>>Hi,
>>
>>Ayone know why I would have terrible graphics performance for some of
>>the newer and older Linux_x86 nvidia drivers except for v1.0.5336 on my
>>quadro 750 xgl card and only for VMD v1.8.2 (not with any other modeling
>>programs e.g. chimera, spdbv, ribbons, turbo, o, etc)?
>>
>>The other driver versions I tested are: 1.0.6229 (latest), 1.0.6111, &
>>1.0.4365 which is "quadro certified" but all of them give really poor
>>performance compared to 1.0.5336 in VMD.
>>
>>These are the settings for all the drivers:
>>
>>glxinfo | grep direct
>>direct rendering: Yes
>>
>>cat /proc/driver/nvidia/agp/status
>>Status: Enabled
>>Driver: NVIDIA
>>AGP Rate: 4x
>>Fast Writes: Enabled
>>SBA: Enabled
>>
>>I also tried switching between agpgart and nvidia's agp for all of the
>>drivers but there is no difference. The system is running under a 2.4.28
>>kernel. I thought it might be related to the issue below so I included
>>the forward.
>>
>>Thanks
>>Sabuj Pattanayek
>>
>>John Stone wrote:
>>
>>>Hi,
>>> Generally speaking, remote rendering will be significantly slower
>>>than local rendering, so you only want to do this when you have no
>>>other choice. This is particularly true for apps that draw a lot of
>>>geometry using immediate mode OpenGL. We've made a large number of
>>>changes in VMD 1.8.3 to make it more remote-display friendly (and faster
>>>in general..) but even so, you'll still notice a big difference between
>>>local and remote display performance.
>>>
>>>You might also experiment with enabling "Display->Cachemode->On" in
>>>the GUI of VMD 1.8.3b1, this enables a feature which can give a huge
>>>performance boost on remote displays, tiled displays, etc.
>>>For the display of a static molecular structure, the display cachemode
>>>feature
>>>should give you anywhere from a 10x to 50x performance boost over normal
>>>rendering. Some machines also get a performance benefit for local
>>>rendering when the caching code is enabled, but that's less frequently the
>>>case than
>>>for remote display. Try that out and let us know how it works for you.
>>>
>>> John
>>>
>>>
>>>On Tue, Dec 28, 2004 at 03:39:32PM +0100, Greipel.Joachim_at_MH-Hannover.DE
>>>wrote:
>>>
>>>
>>>>Hi All,
>>>>I am setting up VMD on a DUAL-Opteron machine for rendering on remote
>>>>X-Servers which run under Linux and are equipped with NVIDA Quadro
>>>>Graphics and Hardware Stereo.
>>>>
>>>>The rendering on the remote machines worked (even stereo display with
>>>>crystal eyes) but unfortunately it was very (!) slow. I just installed
>>>>the 1.8.3b1 version and to my surprise the rendering on the remote
>>>>machines is now acceptably fast.
>>>>
>>>>There are slight differences in the startup messages of VMD
>>>>
>>>>1.8.3b1 ("fast rendering")
>>>>
>>>>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, 2 CPUs detected.
>>>>Info) OpenGL renderer: Quadro4 980 XGL/AGP/SSE2
>>>>Info) Features: STENCIL STEREO RN MDE MTX PP
>>>>Info) OpenGL Programmable shading is NOT available.
>>>>Info) Textures: 2-D (4096x4096), 3-D (512x512x512), Multitexture (4)
>>>>
>>>>1.8.2 ("slow rendering")
>>>>
>>>>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, 2 CPUs detected.
>>>>Info) OpenGL renderer: Quadro4 980 XGL/AGP/SSE2
>>>>Info) Features: STENCIL STEREO RN MTX
>>>>Info) Textures: 2-D (4096x4096), 3-D (512x512x512), Multitexture (4)
>>>>vmd >
>>>>
>>>>Is there any rational explanation for this behaviour?
>>>>Thanks a lot,
>>>>
>>>>Joachim Greipel
>>>>
>>>>Medizinische Hochschule Hannover
>>>>Germany
>>>
>>>
>