[Mesa-users] Internal hardware usage question

[Biddiscombe, John A.]

Hello list,

I have been using mesa for years, but without really knowing much about it. Primarily for doing offscreen rendering in paraview.

I've recently worked with some shaders which I am using for fastish rendering, but I'd like them to work offscreen too, since the data I'll be rendering soon will be large and require parallel compositing etc on a machine like a cray with no GPUs or X servers.

If I implement current shaders with tweaks in GLSL, then they might work with future versions of mesa. (Previous attempts to use shaders with Mesa have proven to be unsatisfactory.) However it occurs to me that redoing the shaders as OpenCL may prove to be more useful as they will work using openGL/CL interop calls and in principle, openCL will compile them to make use of multiple cores (I'm planning ahead here for when the OpenCL compilers are any good). This way, I can do the shading in pure software in OpenCL, take advantage of any hardware acceleration on whichever platform I use, but keep mesa for the existing GL stuff that can't be easily replaced.

My question/s is/are  ....

If I use OpenCL for a shader, will mesa cope with the GL/CL interop sharing of textures/memory etc.
Does mesa internally use any OpenCL-like functionality. It seems like there's no point having openGL any more since the big machines won't support it in hardware (and if I use OpenCL, I'm opening myself to a world of pain getting the two to work well together).
If Mesa used an OpenCL layer internally to do parallel work it'd make sense - but I don't know anything about how mesa is structured. Is anything parallelized internally in Mesa software rendering?

Suppose a vendor produces a machine with many C/GPUs inside, but with no X servers running. Can Mesa make use of these accelerators? (How do the drivers bind to the hardware). (I was always confused as to why mesa - which was supposed to be a software implementation of GL, had hardware drivers at all - have things gone full circle?)

Any help appreciated. As you can see from the contents of this email, I suffer from some confusion about what mesa is supposed to be.

thanks

JB

-- 
John Biddiscombe,                            email:biddisco @ cscs.ch
http://www.cscs.ch/
CSCS, Swiss National Supercomputing Centre  | Tel:  +41 (91) 610.82.07
Via Cantonale, 6928 Manno, Switzerland      | Fax:  +41 (91) 610.82.82