| From: Raj, Ashok <ashok.raj@xxxxxxxxx> | Sent: Wednesday, August 9, 2017 8:58 AM | ... | As Casey pointed out in an earlier thread, we choose the heavy hammer | approach because there are some that can lead to data-corruption as opposed | to perf degradation. Careful. As far as I'm aware, there is no Data Corruption problem whatsoever with Intel Root Ports and processing of Transaction Layer Packets with and without the Relaxed Ordering Attribute set. The only issue which we've discovered with relatively recent Intel Root Port implementations and the use of the Relaxed Ordering Attribute is a performance issue. To the best of our ability to analyze the PCIe traces, it appeared that the Intel Root Complex delayed returning Link Flow Control Credits resulting in lowered performance (total bandwidth). When we used Relaxed Ordering for Ingress Packet Data delivery on a 100Gb/s Ethernet link with 1500-byte MTU, we were pegged at ~75Gb/s. Once we disabled Relaxed Ordering, we were able to deliver Ingress Packet Data to Host Memory at the full link rate. Casey
