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ixgbe: Fix TX stats accounting 

Here is an updated version, because ixgbe_get_ethtool_stats()
needs to call dev_get_stats() or "ethtool -S" wont give
correct tx_bytes/tx_packets values.

Several cpus can update netdev->stats.tx_bytes & netdev->stats.tx_packets
in parallel. In this case, TX stats are under estimated and false sharing
takes place.

After a pktgen session sending exactly 200000000 packets :
# ifconfig fiber0 | grep TX
          TX packets:198501982 errors:0 dropped:0 overruns:0 carrier:0

Multi queue devices should instead use txq->tx_bytes & txq->tx_packets
in their xmit() method (appropriate txq lock already held by caller, no
cache line miss), or use appropriate locking.

After patch, same pktgen session gives :

# ifconfig fiber0 | grep TX
          TX packets:200000000 errors:0 dropped:0 overruns:0 carrier:0

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2009-12-08 07:22:03 +00:00 committed by David S. Miller
parent 3421eecdee
commit 60d5113428
2 changed files with 5 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/net/ixgbe/ixgbe_ethtool.c
View File

@ -990,6 +990,7 @@ static void ixgbe_get_ethtool_stats(struct net_device *netdev,
char *p = NULL;
ixgbe_update_stats(adapter);
dev_get_stats(netdev);
for (i = 0; i < IXGBE_GLOBAL_STATS_LEN; i++) {
switch (ixgbe_gstrings_stats[i].type) {
case NETDEV_STATS:

20
drivers/net/ixgbe/ixgbe_main.c
View File

@ -435,8 +435,6 @@ static bool ixgbe_clean_tx_irq(struct ixgbe_q_vector *q_vector,
tx_ring->total_packets += total_packets;
tx_ring->stats.packets += total_packets;
tx_ring->stats.bytes += total_bytes;
netdev->stats.tx_bytes += total_bytes;
netdev->stats.tx_packets += total_packets;
return (count < tx_ring->work_limit);
}
@ -5327,6 +5325,7 @@ static netdev_tx_t ixgbe_xmit_frame(struct sk_buff *skb,
{
struct ixgbe_adapter *adapter = netdev_priv(netdev);
struct ixgbe_ring *tx_ring;
struct netdev_queue *txq;
unsigned int first;
unsigned int tx_flags = 0;
u8 hdr_len = 0;
@ -5424,6 +5423,9 @@ static netdev_tx_t ixgbe_xmit_frame(struct sk_buff *skb,
tx_ring->atr_count = 0;
}
}
txq = netdev_get_tx_queue(netdev, tx_ring->queue_index);
txq->tx_bytes += skb->len;
txq->tx_packets++;
ixgbe_tx_queue(adapter, tx_ring, tx_flags, count, skb->len,
hdr_len);
ixgbe_maybe_stop_tx(netdev, tx_ring, DESC_NEEDED);
@ -5437,19 +5439,6 @@ static netdev_tx_t ixgbe_xmit_frame(struct sk_buff *skb,
return NETDEV_TX_OK;
}
/**
* ixgbe_get_stats - Get System Network Statistics
* @netdev: network interface device structure
*
* Returns the address of the device statistics structure.
* The statistics are actually updated from the timer callback.
**/
static struct net_device_stats *ixgbe_get_stats(struct net_device *netdev)
{
/* only return the current stats */
return &netdev->stats;
}
/**
* ixgbe_set_mac - Change the Ethernet Address of the NIC
* @netdev: network interface device structure
@ -5580,7 +5569,6 @@ static const struct net_device_ops ixgbe_netdev_ops = {
.ndo_stop = ixgbe_close,
.ndo_start_xmit = ixgbe_xmit_frame,
.ndo_select_queue = ixgbe_select_queue,
.ndo_get_stats = ixgbe_get_stats,
.ndo_set_rx_mode = ixgbe_set_rx_mode,
.ndo_set_multicast_list = ixgbe_set_rx_mode,
.ndo_validate_addr = eth_validate_addr,