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Novice
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Regarding maximum achievable bandwidth via the PCIe (v3, x16) interface for the Intel d5005 board

This question is regarding the maximum achievable bandwidth via the PCIe (v3, x16) interface for the Intel d5005 board.

We did the following tests:

A) Using the streaming_dma_afu example for bandwidth. - 6.7 GBps read, 7.6 GBps write
B) Using the nlb_mode_0 example in LPBK1 mode. - 9 to 9.5 GBps
C) Using OpenCL based 'aoc diagnose all'. - 8.4 GBps

Could someone please let us know why the achievable bandwidth in these tests is almost half of the official specification?

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5 Replies
Employee
77 Views

Hi SNEHA

May you guide us on which part of the official specification doc you are referring to? Thanks.

Eng Wei

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Novice
68 Views

Hi !

The datasheet of D5005 card (link here, go to pg 3 of 29)  specifies it is a PCI Express Gen 3 x16 compliant card. According to the specification of PCI Express, Gen 3 x16 should give bandwidth of 15.75 GB/s (source here). However we are unable to achieve it.

Regards

Sneha

 

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Employee
61 Views

Hi SNEHA 

The spec you are mentioning here is the ideal case for a PCIE transfer rate. The testing you are doing involve the overhead of data transfer from host to FPGA and back to host. We can't compare both the numbers.

Thanks.

Eng Wei

 

 

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Novice
54 Views

Hi!

Thank you for your response. I agree that data transfer from host to FPGA and then back to host involves some overhead and thus the specified bandwidth cannot be reached. However, could you kindly let us know what is the practically achievable maximum bandwidth via PCIe (v3, x16) for d5005 board (considering the overhead)? And, how to achieve it? It would be of great help to us.

Thank you

Regards

Sneha

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Employee
47 Views

Hi Sneha

You can refer to section 5. Running FPGA Diagnostics of https://www.intel.com/content/www/us/en/programmable/documentation/edj1542148561811.html#iyl15486325...

for FPGA diagnostic sample test. The sample results might be different involving various factors of the testing environment.

 

Thanks.

Eng Wei

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