Commit 88340160 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

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: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f2bbca51

include/net/gro_cells.h

+12 −17
Original line number Diff line number Diff line
@@ -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;

}

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