Modify the shared memory size into eight-bytes mode

Dear all,

Recently, I tried to modify shared memory size into eight-bytes size mode with the following instruction:
cudaDeviceSetSharedMemConfig(cudaSharedMemBankSizeEightByte),
But nothing happened, the system still stayed with four-bytes size.

How can I modify the shared memory size?

My GPU is GeForce 840M, which is based on Maxwell GPU Architecture.Does this kind of Architecture support user modify the shared memory bank size?

Thoughts?

Thanks,
Arhur.J

Only Kepler GPUs supported 8 byte mode.