[Intel-gfx] Very low performance when streaming textures

[Marcel Witte]

Hi,

I'm refering to the example of this article about streaming textures and using 
Pixel Buffer Objects: http://www.songho.ca/opengl/gl_pbo.html

The PBO Unpack example (http://www.songho.ca/opengl/files/pboUnpack.zip) is 
creating an "animated texture" and can switch between three modes: Direct 
transfering of the texture using glTexSubImage2D, and using one or two PBOs 
for better performance.

I'm running this example on an notebook with an Intel Core i7-2630QM and an 
Nvidia Geforce GT 550M with Optimus. If I'm using the Nvidia card using 
optirun I get the expected high performance, using direct tranfer about 150 
fps and using PBOs about 400 fps. But if I'm using the intel card I get really 
slow rates, about 40 fps in direct mode and even worse about 10 fps using 
PBOs.

Running the same example with windows I get about 100 fps using the intel card 
in every mode.

Is this expected behaviour or is this a bug in the intel linux driver? How can 
I improve the performance? I hope you can help me here as I'm writing a real 
application using a video as texture.

Regards,
Marcel Witte