I'm doing some GPGPU computing using Opengl and a Nvidia Quadro 2000M card.
While profiling I noticed that my glTexImage2D calls for texture uploads from PBOs are taking 20% of the cpu time, as much as the time spent copying over all the data to the PBOs.
Code :glTexImage2D(GL_TEXTURE_2D, 0, 1, width_, height_, 0, GL_RED, GL_UNSIGNED_BYTE, NULL);
Code :glPixelStorei(GL_UNPACK_ALIGNMENT, 8); glPixelStorei(GL_PACK_ALIGNMENT, 8);
I don't understand why this is taking so much cpu time? Shouldn't it just start the asynchronous DMA transfer to the GPU?