From 7eebb0b28f755e297d355a205bb04945b256db6b Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 17 Apr 2009 22:03:10 +0000 Subject: loopback: packet drops accounting We can in some situations drop packets in netif_rx() loopback driver does not report these (unlikely) drops to its stats, and incorrectly change packets/bytes counts. After this patch applied, "ifconfig lo" can reports these drops as in : # ifconfig lo lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:692562900 errors:3228 dropped:3228 overruns:0 frame:0 TX packets:692562900 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:2865674174 (2.6 GiB) TX bytes:2865674174 (2.6 GiB) I initialy chose to reflect those errors only in tx_dropped/tx_errors, but David convinced me that it was really RX errors, as loopback_xmit() really starts a RX process. (calling eth_type_trans() for example, that itself pulls the ethernet header) These errors are accounted in rx_dropped/rx_errors. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/loopback.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'drivers/net/loopback.c') diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index b7d438a367f3..6f71157bea8e 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -62,6 +62,7 @@ struct pcpu_lstats { unsigned long packets; unsigned long bytes; + unsigned long drops; }; /* @@ -71,18 +72,22 @@ struct pcpu_lstats { static int loopback_xmit(struct sk_buff *skb, struct net_device *dev) { struct pcpu_lstats *pcpu_lstats, *lb_stats; + int len; skb_orphan(skb); - skb->protocol = eth_type_trans(skb,dev); + skb->protocol = eth_type_trans(skb, dev); /* it's OK to use per_cpu_ptr() because BHs are off */ pcpu_lstats = dev->ml_priv; lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id()); - lb_stats->bytes += skb->len; - lb_stats->packets++; - netif_rx(skb); + len = skb->len; + if (likely(netif_rx(skb) == NET_RX_SUCCESS)) { + lb_stats->bytes += len; + lb_stats->packets++; + } else + lb_stats->drops++; return 0; } @@ -93,6 +98,7 @@ static struct net_device_stats *loopback_get_stats(struct net_device *dev) struct net_device_stats *stats = &dev->stats; unsigned long bytes = 0; unsigned long packets = 0; + unsigned long drops = 0; int i; pcpu_lstats = dev->ml_priv; @@ -102,11 +108,14 @@ static struct net_device_stats *loopback_get_stats(struct net_device *dev) lb_stats = per_cpu_ptr(pcpu_lstats, i); bytes += lb_stats->bytes; packets += lb_stats->packets; + drops += lb_stats->drops; } stats->rx_packets = packets; stats->tx_packets = packets; - stats->rx_bytes = bytes; - stats->tx_bytes = bytes; + stats->rx_dropped = drops; + stats->rx_errors = drops; + stats->rx_bytes = bytes; + stats->tx_bytes = bytes; return stats; } -- cgit v1.2.3 From 93f154b594fe47e4a7e5358b309add449a046cd3 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 18 May 2009 22:19:19 -0700 Subject: net: release dst entry in dev_hard_start_xmit() One point of contention in high network loads is the dst_release() performed when a transmited skb is freed. This is because NIC tx completion calls dev_kree_skb() long after original call to dev_queue_xmit(skb). CPU cache is cold and the atomic op in dst_release() stalls. On SMP, this is quite visible if one CPU is 100% handling softirqs for a network device, since dst_clone() is done by other cpus, involving cache line ping pongs. It seems right place to release dst is in dev_hard_start_xmit(), for most devices but ones that are virtual, and some exceptions. David Miller suggested to define a new device flag, set in alloc_netdev_mq() (so that most devices set it at init time), and carefuly unset in devices which dont want a NULL skb->dst in their ndo_start_xmit(). List of devices that must clear this flag is : - loopback device, because it calls netif_rx() and quoting Patrick : "ip_route_input() doesn't accept loopback addresses, so loopback packets already need to have a dst_entry attached." - appletalk/ipddp.c : needs skb->dst in its xmit function - And all devices that call again dev_queue_xmit() from their xmit function (as some classifiers need skb->dst) : bonding, vlan, macvlan, eql, ifb, hdlc_fr Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/loopback.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/net/loopback.c') diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c index 6f71157bea8e..da472c687481 100644 --- a/drivers/net/loopback.c +++ b/drivers/net/loopback.c @@ -170,6 +170,7 @@ static void loopback_setup(struct net_device *dev) dev->tx_queue_len = 0; dev->type = ARPHRD_LOOPBACK; /* 0x0001*/ dev->flags = IFF_LOOPBACK; + dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; dev->features = NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_TSO | NETIF_F_NO_CSUM -- cgit v1.2.3