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My setup:

  • NVIDIA Quadro p6000 (used for GPUDirect)
  • AJA video card (SDI feed from camera and SDI output to the TV)

I am trying to figure out what is the purpose of GPUDirect (in my specific case) if I can achieve the same amount of copying and the same performance using glTexSubImage2D() to fill the GPU texture with any system memory and glGetTextureImageEXT() to get the texture data from the GPU back to any part of system memory.

einpoklum
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Bojan Lovrovic
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    What is "GPU Direct"? – Nicol Bolas Oct 18 '17 at 14:47
  • @NicolBolas: Nvidia's marketing term (AMD uses "DirectGMA") for bus mastered transfers between VRAM and other PCIe devices, – derhass Oct 18 '17 at 16:15
  • It seems that using GPU Direct for AJA and GPU communication is completely avoiding the system memory. That means that glTexSubImage2D() and glGetTextureImageEXT() are less efficient I guess. – Bojan Lovrovic Oct 19 '17 at 16:47
  • How is this related to OpenGL? From the documentation on NVIDIA website I see this tech targets CUDA. – Michael IV Oct 19 '17 at 18:04
  • The only example from AJA card SDK for GPU Direct is using the OpenGL. I have contacted the AJA people and they have told me that using OpenGL is highly recommended. I guess you have to interop it then to the separated CUDA environment? I am not sure... – Bojan Lovrovic Oct 20 '17 at 18:33

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