6 Replies Latest reply on Oct 11, 2010 4:50 AM by waveman

    Can I share a graphics card between graphics and GPGPU?

    waveman
      Is it possible to share a graphics card so it drives by screen and I also do CPU computing on it?

      I assume this is possible but I have not been able to find any explicit confirmation of this.

      I am just starting with GPGPU and my PC only has one PCI-e X16 slot. Currently I have an Nvidia card and my original intention was to use that with CUDA for my programs. The problem is that with Nvidia, if you share the card between graphics and GPGPU you only get 5 seconds to run your program before it times out. Their suggestion is to get a second card. To run two cards I would need a new motherboard, new memory etc, so it is no longer a cost-effective solution.

      So I am looking at an ATI card and Opencl. But before I spend the money I would like to know if I can share the card between graphics and GPGPU and if so, what are the limitations if I do this.

      Thanks,

      Tim Josling

        • Can I share a graphics card between graphics and GPGPU?
          waveman

          I thought it might help to advise my current hardware setup:

          My motherboard is a Gigabyte GA-p35 with 8gm ram

          CPU is Intel(R) Core(TM)2 Quad CPU    Q6600  @ 2.40GHz

          The card I was thinking to buy was something like this

          Gigabyte ATI Radeon HD5870 2GB Eyefinity 6 Edition [R5876P-2GD-B]. (Currently I have an Nvidia 8600 GT).

          I'm running all this on Ubuntu Linix 9.04 but shortly to upgrade to 10.04.

           

          • Can I share a graphics card between graphics and GPGPU?
            waveman

            Based on this post, it looks like I can share the card between video and opencl.


             

            If yours 5870 is attached to the monitor (so it is primary videocard in the OS) some amount of video memory is always used by the system. For example by the desktop window manager (DWM). So you will never get full video memory for your own purposes. I suppose that disabling aero UI or setting 5870 as auxiliary videocard (in another slot) should free this memory and you can try allocate 1Gb piece in video memory.

            And a little advice. You shouldn't try to get the whole memory installed on video card. Driver manages video memory also for its internal services. Render targets, swap chains and so on.


            http://forums.amd.com/devforum/textthread.cfm?catid=328&threadid=139824&filtmsgid=1170736

            It would be good to confirm that there are no constraints other than that total memory usage cannot add up to 100%.

             

             

              • Can I share a graphics card between graphics and GPGPU?
                himanshu.gautam

                hi wavemen,

                AFAIK, the ATI cards can be shared between display and computation.But when a display is attached to them the os binds them to watchdog timer which keeps on checking whether display is available.When this timer goes to zero,it interrupts the computation program and restarts the GPU.However, in ATI Stream Release notes you are given instructions to disable the timer.I am not sure but there should be some way to set this timer in Linux also.

                  • Can I share a graphics card between graphics and GPGPU?
                    nou

                    that 5 second limit is watchdog timer in windows itself. it restart GPU if it doesn't respond. there is way to disable it.

                    there is no such timer on Linux.

                    if you run long running kernels then your GUI will be jerky and bad responsivnes. it is because when on GPU run computation kernel it can't redraw screen. so if your kernel takes 5 second to execute then you do not get 5 second any response except mouse pointer.

                • Can I share a graphics card between graphics and GPGPU?
                  tannergooding

                  I believe it is entirely possible for both ATI and NVIDIA, the reasoning for this is that all DirectX 11 cards support Compute Shaders (which is pretty much just a marketing name provided by Microsoft to sell 'integrated' GPGPU support with DirectX) and DirectX 10 cards support a subset of the Compute Shader specification (limited to number of threads, dispatch, instruction set and type support). As you seem more like a linux fellow, (I myself prefer Windows, but to each his/her own). I assume your using OpenCL/ATI Stream/CUDA, and OpenGL. I'm not quite sure how you would do it on Linux, but I'm sure it's possible since it's supported by the graphics hardware for DirectX 10 & 11.