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Message-ID: <1356832963.21409.6156.camel@edumazet-glaptop>
Date: Sat, 29 Dec 2012 18:02:43 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>
Subject: [PATCH net-next] veth: reduce stat overhead
From: Eric Dumazet <edumazet@...gle.com>
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: Eric Dumazet <edumazet@...gle.com>
---
drivers/net/veth.c | 115 ++++++++++++++----------------------
include/linux/netdevice.h | 1
2 files changed, 48 insertions(+), 68 deletions(-)
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 95814d9..c048f8d 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -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;
+ struct net_device *peer;
+ 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;
-
- u64_stats_update_begin(&stats->syncp);
- stats->tx_bytes += length;
- stats->tx_packets++;
- u64_stats_update_end(&stats->syncp);
+ if (likely(dev_forward_skb(rcv, skb) == NET_RX_SUCCESS)) {
+ struct pcpu_vstats *stats = this_cpu_ptr(dev->vstats);
- 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;
+ u64_stats_update_begin(&stats->syncp);
+ stats->bytes += length;
+ stats->packets++;
+ u64_stats_update_end(&stats->syncp);
+ } else {
+ atomic64_inc(&priv->dropped);
+ }
-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 @@ rx_drop:
* 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);
}
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c599e47..e3f5755 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1274,6 +1274,7 @@ 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;
--
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