RSS does not work (one TCP flow traffic go to more than one queues)

I used MLX CX-5 NIC and CentOS 7 system, with only one TCP flow I found the traffic received from more than one queues. (By checking the output of /proc/interrupts, I found more than one lines’ count increased), that is, RSS function distributed the traffic of this TCP flow to more than one queues.
I also checked the hash fields of hash function with ethtool -n:
[root@testmachine ~]# ethtool -n enp132s0f0 rx-flow-hash tcp4
TCP over IPV4 flows use these fields for computing Hash flow key:
IP SA
IP DA
L4 bytes 0 & 1 [TCP/UDP src port]
L4 bytes 2 & 3 [TCP/UDP dst port]

what’s going on?

Hi,

Thanks for the question.
/proc/interrupts may not always accurately reflect what RX q is getting traffic.
To check what RX q is getting traffic you can try ethtool -S command, or mlnx_perf -i

Best Regards,
Anatoly