On Tue, 21 Oct 2008, Stephen Hemminger wrote:
> The network statistics were being updated by multiple CPU's causing cache
> line bounces. Since this driver already keeps statistics per ring, use
> those to compute the bytes/packet statistics.
>
> Signed-off-by: Stephen Hemminger <[EMAIL PROTECTED]>
Yeah, this is code we developed for e1000(e) and that was for only one
queue, it should be a problem, and we should fix it one way or another.
Thanks Stephen, everything seems good after a quick review, except for one
note: see below.
> Compile tested only, evaluation in progress
okay
> --- a/drivers/net/igb/igb_main.c 2008-10-21 08:57:11.000000000 -0700
> +++ b/drivers/net/igb/igb_main.c 2008-10-21 09:05:43.000000000 -0700
> @@ -3029,9 +3029,27 @@ static struct net_device_stats *
> igb_get_stats(struct net_device *netdev)
> {
> struct igb_adapter *adapter = netdev_priv(netdev);
> + struct net_device_stats *stats = &adapter->net_stats;
> + int i;
> +
> + stats->tx_bytes = 0;
> + stats->tx_packets = 0;
> + for (i = 0; i < adapter->num_tx_queues; i++) {
> + struct igb_ring *tx_ring = &adapter->tx_ring[i];
> + stats->tx_bytes += tx_ring->tx_stats.bytes;
> + stats->tx_packets += tx_ring->tx_stats.packets;
> + }
> + stats->rx_bytes = 0;
> + stats->rx_packets = 0;
> + for (i = 0; i < adapter->num_rx_queues; i++) {
> + struct igb_ring *rx_ring = &adapter->rx_ring[i];
> + stats->rx_bytes += rx_ring->rx_stats.bytes;
> + stats->rx_packets += rx_ring->rx_stats.packets;
> + }
> +
> + igb_update_stats(adapter);
I don't think you want to put this in the code that can be called directly
from IOCTL from userspace. This function can take a lot of cycles and
some silly applications like gkrellm call it quite frequently. The
update_stats function will be called as part of the watchdog anyway, and
you already got the interesting stats for realtime with the tx and rx
bytes/packets.
> - /* only return the current stats */
> - return &adapter->net_stats;
> + return stats;
> }
>
> /**
> @@ -3711,8 +3729,6 @@ done_cleaning:
> tx_ring->total_packets += total_packets;
> tx_ring->tx_stats.bytes += total_bytes;
> tx_ring->tx_stats.packets += total_packets;
> - adapter->net_stats.tx_bytes += total_bytes;
> - adapter->net_stats.tx_packets += total_packets;
> return retval;
> }
>
> @@ -3953,8 +3969,6 @@ next_desc:
> rx_ring->total_bytes += total_bytes;
> rx_ring->rx_stats.packets += total_packets;
> rx_ring->rx_stats.bytes += total_bytes;
> - adapter->net_stats.rx_bytes += total_bytes;
> - adapter->net_stats.rx_packets += total_packets;
> return cleaned;
> }
The same thing should be done to ixgbe too, but I'm just mentioning it for
posterity, not because I'd expect you to do so.
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