General Discussions

[tbr_rt]

Hello,

We have some AMD CPUs at our disposal:

• AMD Ryzen 7 7700 (Zen 4), motherboard: Supermicro H13SAE
• AMD Ryzen 5 7600X (Zen 4), motherboard: ASrock B650D4U-2L2T
• AMD Ryzen 5 3600XT (Zen 2), motherboard: ASRock X570D4U-2L2T

We tested FPGA communication using DMA transfer with the following environment:

• Linux OS with a custom kernel using isolcpus.
• IOMMU disabled.
• Series 7 FPGA or Dolphin RDMA cards (https://www.dolphinics.com/products/MXH930.html).

On the Zen 2 setup, the performance is deterministic. However, on the two Zen 4 setups, I experience jitter in our userspace process (the process is interrupted by 1 to 4 microseconds) when I activate DMA transfer.

Any hints or advice would be appreciated.