Hash rss value with mprq_en=1 device parameter

Hash rss value with mprq_en=1 device parameter

[Дмитрий Степанов]

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Hi folks!

I'm using Mellanox ConnectX-6 Dx EN adapter card (100GbE; Dual-port QSFP56;
PCIe 4.0/3.0 x16) with DPDK 21.11.
I'm setting mprq_en=1 device parameter to increase rx performance. But in
that case, rte_mbuf's field `hash.rss` of the received frame is zero and
`RTE_MBUF_F_RX_RSS_HASH` flag of field `ol_flags` is not set.
Without mprq_en=1 i get valid `hash.rss` value and flag
`RTE_MBUF_F_RX_RSS_HASH` is set.
Is there any way to get valid `hash.rss` value with mprq_en=1?

Thanks,
Dmitriy Stepanov

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Re: Hash rss value with mprq_en=1 device parameter

[Dmitry Kozlyuk]

Looks like a case described in PMD docs
(https://doc.dpdk.org/guides/nics/mlx5.html):

	If Multi-Packet Rx queue is configured (mprq_en) and Rx CQE compression
	is enabled (rxq_cqe_comp_en) at the same time, RSS hash result is not
	fully supported. Some Rx packets may not have RTE_MBUF_F_RX_RSS_HASH.

I recommend checking that page in general, because mlx5 PMD supports many
features, but not all combinations of them.