From 88340160f3ad22401b00f4efcee44f7ec4769b19 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Fri, 16 Jan 2015 10:11:00 -0800 Subject: [PATCH] ip_tunnel: Create percpu gro_cell In the ipip tunnel, the skb->queue_mapping is lost in ipip_rcv(). All skb will be queued to the same cell->napi_skbs. The gro_cell_poll is pinned to one core under load. In production traffic, we also see severe rx_dropped in the tunl iface and it is probably due to this limit: skb_queue_len(&cell->napi_skbs) > netdev_max_backlog. This patch is trying to alloc_percpu(struct gro_cell) and schedule gro_cell_poll to process the skb in the same core. Signed-off-by: Martin KaFai Lau Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/gro_cells.h | 29 ++++++++++++----------------- 1 file changed, 12 insertions(+), 17 deletions(-) diff --git a/include/net/gro_cells.h b/include/net/gro_cells.h index 734d9b5f577a..0f712c0bc0bf 100644 --- a/include/net/gro_cells.h +++ b/include/net/gro_cells.h @@ -8,25 +8,23 @@ struct gro_cell { struct sk_buff_head napi_skbs; struct napi_struct napi; -} ____cacheline_aligned_in_smp; +}; struct gro_cells { - unsigned int gro_cells_mask; - struct gro_cell *cells; + struct gro_cell __percpu *cells; }; static inline void gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb) { - struct gro_cell *cell = gcells->cells; + struct gro_cell *cell; struct net_device *dev = skb->dev; - if (!cell || skb_cloned(skb) || !(dev->features & NETIF_F_GRO)) { + if (!gcells->cells || skb_cloned(skb) || !(dev->features & NETIF_F_GRO)) { netif_rx(skb); return; } - if (skb_rx_queue_recorded(skb)) - cell += skb_get_rx_queue(skb) & gcells->gro_cells_mask; + cell = this_cpu_ptr(gcells->cells); if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) { atomic_long_inc(&dev->rx_dropped); @@ -72,15 +70,12 @@ static inline int gro_cells_init(struct gro_cells *gcells, struct net_device *de { int i; - gcells->gro_cells_mask = roundup_pow_of_two(netif_get_num_default_rss_queues()) - 1; - gcells->cells = kcalloc(gcells->gro_cells_mask + 1, - sizeof(struct gro_cell), - GFP_KERNEL); + gcells->cells = alloc_percpu(struct gro_cell); if (!gcells->cells) return -ENOMEM; - for (i = 0; i <= gcells->gro_cells_mask; i++) { - struct gro_cell *cell = gcells->cells + i; + for_each_possible_cpu(i) { + struct gro_cell *cell = per_cpu_ptr(gcells->cells, i); skb_queue_head_init(&cell->napi_skbs); netif_napi_add(dev, &cell->napi, gro_cell_poll, 64); @@ -91,16 +86,16 @@ static inline int gro_cells_init(struct gro_cells *gcells, struct net_device *de static inline void gro_cells_destroy(struct gro_cells *gcells) { - struct gro_cell *cell = gcells->cells; int i; - if (!cell) + if (!gcells->cells) return; - for (i = 0; i <= gcells->gro_cells_mask; i++,cell++) { + for_each_possible_cpu(i) { + struct gro_cell *cell = per_cpu_ptr(gcells->cells, i); netif_napi_del(&cell->napi); skb_queue_purge(&cell->napi_skbs); } - kfree(gcells->cells); + free_percpu(gcells->cells); gcells->cells = NULL; }