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7th
04-23-2007, 08:25 AM
Hi,
I have seen a few snippets of info around that talk about issues with (recent) nVidia drivers causing a significant 'stall' when uniforms are updated that effectively alter the code path through the fragment shader.

This is certainly a problem that I am seeing (only on newer drivers), and it has been suggested that the problem is caused by the driver re-compiling the shader beause of 'optimisations' that were made at initial compile time.

Is there a way of disabling this? The stall that occurs is killing the realtime of our app.

FYI - the stall occurs only the 1st time a shader is used after a uniform altered that changes the code path.

It is not very practicle for me to re-write the shader so that I do not have this behaviour, and even if it was I do not have any confidence that it would not break in the next release of driver.

Any thoughts would be most welcome!

Cheers.

ZbuffeR
04-23-2007, 04:58 PM
Ask nvidia.
Then please post their response.

Frogblast
04-23-2007, 06:20 PM
Please poke Nvidia about it. I recently was working with a demo that was running at >200fps on a X1600, and <30 on a 7600GT, due to this very issue.