Today, the NVIDA 418.67 driver became available to me.
In an FFT of size 8096 using cuComplex type, the precision of the output has been reduced in a significant way. Using numpy’s allclose we were testing a knowing input signal, the rtol parameter absolute(a - b) <= (atol + rtol * absolute(b)) used to function at 1e-05. And now will only function with relative tolerance of 1e-04.
Is this known and expected behavior? Or is there an issue in our usage?
The CUFFT library itself doesn’t change when a new driver comes out. It’s not impossible for a driver to have an effect, but unlikely to be noticeable.
On the other hand CUDA 10.1 Update 1 did also become available (which depends on this newer driver 418.67) so if you actually installed CUDA 10.0 Update 1, it brought a new version of CUFFT library with it. There were definitely changes in CUFFT library from CUDA 10.1 to CUDA 10.1 Update 1.
I doubt this is known and expected behavior. I couldn’t comment whether there is an issue in your usage, since I have no idea what your usage is. If you can provide a complete test case, that would certainly help. In that case, you could file a bug if you wish. The instructions to do so are linked at the top of the CUDA programming forum.
Thank you Robert. I will do further analysis to confirm if an issue in fact exists, and if so will follow the guidelines documented here: https://devtalk.nvidia.com/default/topic/1044668/cuda-programming-and-performance/-how-to-report-a-bug/