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

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 <>
Acked-by: default avatarEric Dumazet <>
Signed-off-by: default avatarDavid S. Miller <>
parent f2bbca51
......@@ -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)) {
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) {
......@@ -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),
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);
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)
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);
gcells->cells = NULL;
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