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Commit 2681128f authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

veth: reduce stat overhead 



veth stats are a bit bloated. There is no need to account transmit
and receive stats, since they are absolutely symmetric.

Also use a per device atomic64_t for the dropped counter, as it
should never be used in fast path.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4cafe373

drivers/net/veth.c

+47 −68
Original line number Diff line number Diff line
@@ -25,18 +25,15 @@ 
#define MIN_MTU 68		/* Min L3 MTU */

#define MAX_MTU 65535		/* Max L3 MTU (arbitrary) */



struct veth_net_stats {

	u64			rx_packets;

	u64			rx_bytes;

	u64			tx_packets;

	u64			tx_bytes;

	u64			rx_dropped;

struct pcpu_vstats {

	u64			packets;

	u64			bytes;

	struct u64_stats_sync	syncp;

};



struct veth_priv {

	struct net_device	*peer;

	struct veth_net_stats __percpu *stats;

	atomic64_t		dropped;

};



/*
@@ -107,50 +104,30 @@ static const struct ethtool_ops veth_ethtool_ops = { 
	.get_ethtool_stats	= veth_get_ethtool_stats,

};



/*

 * xmit

 */



static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)

{

	struct net_device *rcv = NULL;

	struct veth_priv *priv, *rcv_priv;

	struct veth_net_stats *stats, *rcv_stats;

	int length;



	priv = netdev_priv(dev);

	rcv = priv->peer;

	rcv_priv = netdev_priv(rcv);



	stats = this_cpu_ptr(priv->stats);

	rcv_stats = this_cpu_ptr(rcv_priv->stats);

	struct veth_priv *priv = netdev_priv(dev);

	struct net_device *rcv = priv->peer;

	int length = skb->len;



	/* don't change ip_summed == CHECKSUM_PARTIAL, as that

	   will cause bad checksum on forwarded packets */

	 * will cause bad checksum on forwarded packets

	 */

	if (skb->ip_summed == CHECKSUM_NONE &&

	    rcv->features & NETIF_F_RXCSUM)

		skb->ip_summed = CHECKSUM_UNNECESSARY;



	length = skb->len;

	if (dev_forward_skb(rcv, skb) != NET_RX_SUCCESS)

		goto rx_drop;

	if (likely(dev_forward_skb(rcv, skb) == NET_RX_SUCCESS)) {

		struct pcpu_vstats *stats = this_cpu_ptr(dev->vstats);



		u64_stats_update_begin(&stats->syncp);

	stats->tx_bytes += length;

	stats->tx_packets++;

		stats->bytes += length;

		stats->packets++;

		u64_stats_update_end(&stats->syncp);

	} else {

		atomic64_inc(&priv->dropped);

	}



	u64_stats_update_begin(&rcv_stats->syncp);

	rcv_stats->rx_bytes += length;

	rcv_stats->rx_packets++;

	u64_stats_update_end(&rcv_stats->syncp);



	return NETDEV_TX_OK;



rx_drop:

	u64_stats_update_begin(&rcv_stats->syncp);

	rcv_stats->rx_dropped++;

	u64_stats_update_end(&rcv_stats->syncp);

	return NETDEV_TX_OK;

}
@@ -158,32 +135,42 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev) 
 * general routines

 */



static struct rtnl_link_stats64 *veth_get_stats64(struct net_device *dev,

						  struct rtnl_link_stats64 *tot)

static u64 veth_stats_one(struct pcpu_vstats *result, struct net_device *dev)

{

	struct veth_priv *priv = netdev_priv(dev);

	int cpu;



	result->packets = 0;

	result->bytes = 0;

	for_each_possible_cpu(cpu) {

		struct veth_net_stats *stats = per_cpu_ptr(priv->stats, cpu);

		u64 rx_packets, rx_bytes, rx_dropped;

		u64 tx_packets, tx_bytes;

		struct pcpu_vstats *stats = per_cpu_ptr(dev->vstats, cpu);

		u64 packets, bytes;

		unsigned int start;



		do {

			start = u64_stats_fetch_begin_bh(&stats->syncp);

			rx_packets = stats->rx_packets;

			tx_packets = stats->tx_packets;

			rx_bytes = stats->rx_bytes;

			tx_bytes = stats->tx_bytes;

			rx_dropped = stats->rx_dropped;

			packets = stats->packets;

			bytes = stats->bytes;

		} while (u64_stats_fetch_retry_bh(&stats->syncp, start));

		tot->rx_packets += rx_packets;

		tot->tx_packets += tx_packets;

		tot->rx_bytes   += rx_bytes;

		tot->tx_bytes   += tx_bytes;

		tot->rx_dropped += rx_dropped;

		result->packets += packets;

		result->bytes += bytes;

	}

	return atomic64_read(&priv->dropped);

}



static struct rtnl_link_stats64 *veth_get_stats64(struct net_device *dev,

						  struct rtnl_link_stats64 *tot)

{

	struct veth_priv *priv = netdev_priv(dev);

	struct pcpu_vstats one;



	tot->tx_dropped = veth_stats_one(&one, dev);

	tot->tx_bytes = one.bytes;

	tot->tx_packets = one.packets;



	tot->rx_dropped = veth_stats_one(&one, priv->peer);

	tot->rx_bytes = one.bytes;

	tot->rx_packets = one.packets;



	return tot;

}
@@ -228,24 +215,16 @@ static int veth_change_mtu(struct net_device *dev, int new_mtu) 


static int veth_dev_init(struct net_device *dev)

{

	struct veth_net_stats __percpu *stats;

	struct veth_priv *priv;



	stats = alloc_percpu(struct veth_net_stats);

	if (stats == NULL)

	dev->vstats = alloc_percpu(struct pcpu_vstats);

	if (!dev->vstats)

		return -ENOMEM;



	priv = netdev_priv(dev);

	priv->stats = stats;

	return 0;

}



static void veth_dev_free(struct net_device *dev)

{

	struct veth_priv *priv;



	priv = netdev_priv(dev);

	free_percpu(priv->stats);

	free_percpu(dev->vstats);

	free_netdev(dev);

}

include/linux/netdevice.h

+1 −0
Original line number Diff line number Diff line
@@ -1284,6 +1284,7 @@ struct net_device { 
		struct pcpu_lstats __percpu	*lstats; /* loopback stats */

		struct pcpu_tstats __percpu	*tstats; /* tunnel stats */

		struct pcpu_dstats __percpu	*dstats; /* dummy stats */

		struct pcpu_vstats __percpu	*vstats; /* veth stats */

	};

	/* GARP */

	struct garp_port __rcu	*garp_port;