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Old 06-04-12, 03:12 PM   #1
tdsussman
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Join Date: Jun 2012
Posts: 3
Default GPU memory consumption, back buffer, Quadro

The use of glScissor when drawing into the back buffer causes the GPU memory requirement to continually increase.

Please see the attached simple OpenGL program glxtest.c. It is run using

./glxtest.exe (ibufse) (iscissor)

in which

ibufse=1: draw to front buffer
ibufse=2: draw to back buffer

iscissor=0: do not scissor when clearing
iscissor=1: scissor when clearing

./glxtest.exe 2 1

draws to the back buffer repeately, scissoring when clearing the screen.

Observe that

GPU_MEMORY_INFO_CURRENT_AVAILABLE_MEMORY_NVX

continually decreases. The memory of the process reported by 'top'
also continually increases.

If I don't scissor

./glxtest.exe 2 0

or if I scissor into the front buffer

./glxtest.exe 1 1

then the memory doesn't increase.

I am running Red Hat Enterprise Linux 5 (kernel 2.6.18-8.e15) on an x86_64 platform.
Driver: NVIDIA 295.53, as downloaded from the NVIDIA website.
Graphics card: QUADRO FX 570, 256 MB memory.

I have attached nvidia-bug-report.log.gz.

Is this memory increase a bug in the NVIDIA drivers for Linux? If so, should I report the
bug directly to NVIDIA?

Thank you.
Attached Files
File Type: gz nvidia-bug-report.log.gz (73.3 KB, 68 views)
File Type: zip glxtest.zip (2.9 KB, 78 views)

Last edited by tdsussman; 06-08-12 at 04:12 PM. Reason: more information
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