You’re getting 47GB/s for D2D on bandwidthTest. You previously said this:
“I have try bandwidthTest and the results was almost the same.”
I would not agree with that statement, and in fact would say it is misleading, given that bandwidthTest is reporting 47GB/s not some number that is approximately 30GB/s which is what you originally reported at this statement:
“But when i run the code from the link the result is about 30GB.”
So I go back to my original statement:
“I’m not sure the code presented in that link is intended to be a good measure of “best achievable bandwidth”.”
Your GPU peak theoretical bw is 64GB/s, and the achievable bandwidth (as reported by bandwidthTest) is 47GB/s.
These are expected results, and the fact that you don’t get 47GB/s from the code in the first link you gave does not mean that there is something wrong with your system or that your calculations are incorrect, it means that
that code will not give a reliable estimate of the available bandwidth.
The text in that link states:
“We can modify our SAXPY example to calculate the effective bandwidth.”
This is not the peak theoretical bandwidth, nor is it the maximum achievable bandwidth. It is the bandwidth achieved by that particular saxpy example. The fact that it is at 30GB/s vs. 47 achievable means that that particular code (or perhaps the way you compiled it) will not achieve the max available bandwidth.