I am running the bandwitdhTest.exe code from SDK on Tesla c2050 on Windows Server 2008 R2 machine. I have PCI Express x16 gen2.
I see Host-Device bandwidth of 3GB/s which becomes 6GB/s with pinned memory.
I was expecting higher bandwith, what could be the problem?
The non-pinned variant requires a copy in system memory on the host side (user memory <-> pinned DMA buffer), so the performance depends heavily on the system memory performance of the host. The latest x86 platforms have very good system memory throughput; on these the difference between the pinned and non-pinned cases is much smaller than on older systems where the throughput of system memory wasn’t much higher than the throughput of PCIe gen2. From the numbers posted, zeus13i seems to have such a latest generation x86 host system.