nvcc warning in cuda 8.0

Question

I am getting this warning when I try to execute nvcc.

I have cuda toolket 8.0 I have Nvidia GTX 480 in my system.

nvcc warning : The 'compute_20', 'sm_20', and 'sm_21' architectures are deprecated, and may be removed in a future release (Use -Wno-deprecated-gpu-targets to suppress warning).

Can anyone explain this warning?

Please let me know if you need more information.

Answer 1

This is the CUDA development teams (i.e. NVIDIA) way of letting CUDA developers (i.e. you) know that compute capability (cc) 2.x devices won't be supported for much longer.

It's reasonable to assume that the next major CUDA release will drop support for compute capability 2.x devices, including your GTX 480. Therefore, CUDA 8.0 is likely the last CUDA toolkit that will support that device.

The warning occurs even if no target architecture is specified, because the default target architecture for CUDA 8 is cc 2.0.

If you only intend to target devices of cc3.0 or higher, you can eliminate the warning from your compile output by specifying an appropriate architecture to match your devices, e.g.

nvcc -arch=sm_30 ...

for example to target cc 3.0 and higher devices. As the warning message itself indicates, you can also specify a command line switch to suppress the warning.

Something similar happened in the CUDA 6.x timeframe when support for cc 1.x devices was deprecated. Support was dropped in CUDA 7.0.