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Commit c9e6bc64 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: add gro_cells infrastructure 



This adds a new include file (include/net/gro_cells.h), to bring GRO
(Generic Receive Offload) capability to tunnels, in a modular way.

Because tunnels receive path is lockless, and GRO adds a serialization
using a napi_struct, I chose to add an array of up to
DEFAULT_MAX_NUM_RSS_QUEUES cells, so that multi queue devices wont be
slowed down because of GRO layer.

skb_get_rx_queue() is used as selector.

In the future, we might add optional fanout capabilities, using rxhash
for example.

With help from Ben Hutchings who reminded me
netif_get_num_default_rss_queues() function.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 861b6501

include/net/gro_cells.h

0 → 100644
+103 −0
Original line number Original line Diff line number Diff line 
#ifndef _NET_GRO_CELLS_H

#define _NET_GRO_CELLS_H



#include <linux/skbuff.h>

#include <linux/slab.h>

#include <linux/netdevice.h>



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;

};



static inline void gro_cells_receive(struct gro_cells *gcells, struct sk_buff *skb)

{

	unsigned long flags;

	struct gro_cell *cell = gcells->cells;

	struct net_device *dev = skb->dev;



	if (!cell || 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;



	if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) {

		atomic_long_inc(&dev->rx_dropped);

		kfree_skb(skb);

		return;

	}



	spin_lock_irqsave(&cell->napi_skbs.lock, flags);



	__skb_queue_tail(&cell->napi_skbs, skb);

	if (skb_queue_len(&cell->napi_skbs) == 1)

		napi_schedule(&cell->napi);



	spin_unlock_irqrestore(&cell->napi_skbs.lock, flags);

}



static inline int gro_cell_poll(struct napi_struct *napi, int budget)

{

	struct gro_cell *cell = container_of(napi, struct gro_cell, napi);

	struct sk_buff *skb;

	int work_done = 0;



	while (work_done < budget) {

		skb = skb_dequeue(&cell->napi_skbs);

		if (!skb)

			break;



		napi_gro_receive(napi, skb);

		work_done++;

	}



	if (work_done < budget)

		napi_complete(napi);

	return work_done;

}



static inline int gro_cells_init(struct gro_cells *gcells, struct net_device *dev)

{

	int i;



	gcells->gro_cells_mask = roundup_pow_of_two(netif_get_num_default_rss_queues()) - 1;

	gcells->cells = kcalloc(sizeof(struct gro_cell),

				gcells->gro_cells_mask + 1,

				GFP_KERNEL);

	if (!gcells->cells)

		return -ENOMEM;



	for (i = 0; i <= gcells->gro_cells_mask; i++) {

		struct gro_cell *cell = gcells->cells + i;



		skb_queue_head_init(&cell->napi_skbs);

		netif_napi_add(dev, &cell->napi, gro_cell_poll, 64);

		napi_enable(&cell->napi);

	}

	return 0;

}



static inline void gro_cells_destroy(struct gro_cells *gcells)

{

	struct gro_cell *cell = gcells->cells;

	int i;



	if (!cell)

		return;

	for (i = 0; i <= gcells->gro_cells_mask; i++,cell++) {

		netif_napi_del(&cell->napi);

		skb_queue_purge(&cell->napi_skbs);

	}

	kfree(gcells->cells);

	gcells->cells = NULL;

}



#endif

net/core/dev.c

+2 −0
Original line number Original line Diff line number Diff line
@@ -2645,6 +2645,8 @@ EXPORT_SYMBOL(dev_queue_xmit); 
  =======================================================================*/

  =======================================================================*/





int netdev_max_backlog __read_mostly = 1000;

int netdev_max_backlog __read_mostly = 1000;

EXPORT_SYMBOL(netdev_max_backlog);



int netdev_tstamp_prequeue __read_mostly = 1;

int netdev_tstamp_prequeue __read_mostly = 1;

int netdev_budget __read_mostly = 300;

int netdev_budget __read_mostly = 300;

int weight_p __read_mostly = 64;            /* old backlog weight */

int weight_p __read_mostly = 64;            /* old backlog weight */