From: Eric Dumazet <eric.duma...@gmail.com> Date: Sun, 20 Nov 2016 09:24:36 -0800
> From: Eric Dumazet <eduma...@google.com> > > 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 <eduma...@google.com> Applied.
