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f3483c8e1d
RFS is using two kinds of hash tables. First one is controlled by /proc/sys/net/core/rps_sock_flow_entries = 2^N and using the N low order bits of the l4 hash is good enough. Then each RX queue has its own hash table, controlled by /sys/class/net/eth1/queues/rx-$q/rps_flow_cnt = 2^X Current hash function, using the X low order bits is suboptimal, because RSS is usually using Func(hash) = (hash % power_of_two); For example, with 32 RX queues, 6 low order bits have no entropy for a given queue. Switch this hash function to hash_32(hash, log) to increase chances to use all possible slots and reduce collisions. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Tom Herbert <tom@herbertland.com> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20250321171309.634100-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>