Controller P2P bandwidth

[jordon_chang]

Hi all,

I tried to measure the peer to peer streaming rate of PXIe-1088 by using FPGA system with Labview 2018.

I use PXIe-5785 as writer, PXIe-7976 as reader, representation is I16 and write 8 data into FIFO each time.

According to 1088 manual, slot 4,6,8 should has 2 GB/s bandwidth so I plug 5785 into slot 4, 7976 into slot 6. From the backplane of 1088,

P2P streaming path would go through the PCIe switch in controller. Then I choose PXIe-8133 as controller.

From NI ocumentation(https://www.ni.com/en/support/documentation/supplemental/10/an-introduction-to-peer-to-peer-streamin...), maximum rate between switches of 8133 is 1.6 GB/s, maximum peer-to-peer rate of 7976 and 5785 are 3.2 GB/s and 7 GB/s.

But it only reach about 902 MB/s. Are there anything I missing or wrong?

Moreover, I change controller to 8880, the streaming rate increase to about 1.4 GB/s.

It seems the PCIe switch in the 8133 limits the streaming rate but maximum rate between switches of 8133 is 1.6 GB/s. Is any setting I missing?

By the way, where can I find the maximum rate between switches of 8880? I do not find in document and 8880 user's manual.