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Eric Dumazet authored
While stressing a 40Gbit mlx4 NIC with busy polling, I found false sharing in mlx4 driver that can be easily avoided. This patch brings an additional 7 % performance improvement in UDP_RR workload. 1) If we received no frame during one mlx4_en_process_rx_cq() invocation, no need to call mlx4_cq_set_ci() and/or dirty ring->cons 2) Do not refill rx buffers if we have plenty of them. This avoids false sharing and allows some bulk/batch optimizations. Page allocator and its locks will thank us. Finally, mlx4_en_poll_rx_cq() should not return 0 if it determined cpu handling NIC IRQ should be changed. We should return budget-1 instead, to not fool net_rx_action() and its netdev_budget. v2: keep AVG_PERF_COUNTER(... polled) even if polled is 0 Signed-off-by:
Eric Dumazet <edumazet@google.com> Cc: Tariq Toukan <tariqt@mellanox.com> Reviewed-by:
Tariq Toukan <tariqt@mellanox.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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