How to increase the speed of submatrix data transfer using gpuArray rather than CPU?

Hello. My problem is... How can I reduce the difference btw. them? The size of matrix is smaller than 1000 by 1000. If possible (whether this is intrinsic limitation) please tell me a proper method.

A = rand(512);
gA = gpuArray(A);
tic; B = A(50:100,50:100); toc
tic; gB = gA(50:100,50:100); toc

Answer 1

[Walter Roberson]

Instead of using tic and toc, use timeit() for the first case, and gputimeit() for the second case. Those will give you more accurate times.

[Sung Hwan Heo]

Already did that, but there was no big changes @.@;;;

Answer 2

[Joss Knight]

I think the problem is intrinsic. Even on my Kepler K20c the GPU is slower for this case. This is a memory intensive non-coherent operation and you don't have enough data.

Best solution: Try to do more! Perhaps if you're doing this same indexing to multiple matrices, you should do them all at once, for instance.