[PATCH] doc: document hash RSS limitations with CQE zipping

[PATCH] doc: document hash RSS limitations with CQE zipping

[Alexander Kozyrev]

RSS hash is only fully supported when the Hash RSS format is selected.
Update MLX5 documentation about lack of RTE_MBUF_F_RX_RSS_HASH flag for
some packets in case of any other CQE compression format is configured.

Signed-off-by: Alexander Kozyrev <akozyrev@nvidia.com>
---
 doc/guides/nics/mlx5.rst | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 30c40f767b..ceea2dd320 100644
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -497,9 +497,12 @@ Limitations
   cannot be used in conjunction with MPRQ
   since packets may be already attached to PMD-managed external buffers.
 
-- If Multi-Packet Rx queue is configured (``mprq_en``) and Rx CQE compression is
+- RSS hash result is only fully supported when the Hash RSS format is selected
+  as the current CQE compression format on the RX side (``rxq_cqe_comp_en``).
+  Any other format leads to no RTE_MBUF_F_RX_RSS_HASH flag for some Rx packets.
+  If a 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.
+  supported, as the Checksum format is selected by default in this case.
 
 - IPv6 Multicast messages are not supported on VM, while promiscuous mode
   and allmulticast mode are both set to off.
-- 
2.43.5

RE: [PATCH] doc: document hash RSS limitations with CQE zipping

[Dariusz Sosnowski]

> -----Original Message-----
> From: Alexander Kozyrev <akozyrev@nvidia.com>
> Sent: Thursday, January 9, 2025 23:34
> To: dev@dpdk.org
> Cc: Raslan Darawsheh <rasland@nvidia.com>; Slava Ovsiienko
> <viacheslavo@nvidia.com>; Dariusz Sosnowski <dsosnowski@nvidia.com>;
> Bing Zhao <bingz@nvidia.com>; Suanming Mou <suanmingm@nvidia.com>
> Subject: [PATCH] doc: document hash RSS limitations with CQE zipping
> 
> RSS hash is only fully supported when the Hash RSS format is selected.
> Update MLX5 documentation about lack of RTE_MBUF_F_RX_RSS_HASH flag
> for some packets in case of any other CQE compression format is configured.
> 
> Signed-off-by: Alexander Kozyrev <akozyrev@nvidia.com>

Acked-by: Dariusz Sosnowski <dsosnowski@nvidia.com>

Best regards,
Dariusz Sosnowski