Thanks you for posting your question on the Mellanox Community.
Based on the information provided, the following Mellanox Community document explains the 'rx_out_of_buffer' ethtool/xstat statistic.
You can improve the rx_out_of_buffer behavior with tuning the node and also modifying the ring-size on the adapter (ethtool -g <int>)
Also make sure, you follow the DPDK Performance recommendations from the following link -> https://doc.dpdk.org/guides/nics/mlx5.html#performance-tuning
If you still experience performance issues after these recommendations, please do not hesitate to open a Mellanox Support Case, by emailing to firstname.lastname@example.org
Thanks and regards,
~Mellanox Technical Support
Thanks for the answer ! But I don't see what you refer as "the following Mellanox Community document" ? So I kind of still don't know what it is. If you refer to the line "Number of times receive queue had no software buffers allocated for the adapter's incoming traffic.", then the tuning you mention will not change the problem because the rings are never full, and the CPU is not busy. So what buffer does "rx-out-of-buffer" count if it's not the ring buffers?