Hello Alexander,
Mellanox is testing latency using RFC2544 FIFO by packet size .
Please see our Tolly Reports : http://www.mellanox.com/related-docs/products/Tolly-215111-Mellanox-SwitchX-2_Performance.pdf
We do not see how exalink fusion is testing the latency , we suggest you should ask them on their forum
Best Regards,
Michael.