A prolem of CUDAGL & gldrawElements CUDAGL

The OPENGL function:

need the count of index buffer,
and cudaGL functions can bind it with GPU memory

the problem is that
I’ve done index reduction with CUDA,so the count of index buffer is changed and it’s
in GPU memory.

And the performance of cudaMemcpy is … so terrible
How can I map the count with GPU memory?

thx :">