netdev - Re: RX/dropped counter values for tagged packets

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Date:	Sat, 30 Mar 2013 20:30:51 -0700
From:	Ani Sinha <ani@...stanetworks.com>
To:	netdev@...r.kernel.org, linuxdev@...rban.org
Subject: Re: RX/dropped counter values for tagged packets

Hi guys,

any feedback on this will be highly appreciated.

thanks,

ani


On Sun, Mar 24, 2013 at 9:43 PM, Ani Sinha <ani@...stanetworks.com> wrote:
> hello everyone :
>
> Please bear with me if you think I said something wrong.
>
> I was looking at the netif_receive_skb() code and it seems to me that
> for vlan tagged packets, the counters are manipulated at two different
> places. One is from vlan_do_receive() where the receive counters are
> incremented. The other counter (the dropped counter) is incremented at
> the very end of netif_receive_skb() when there are no takers for this
> packet. The dropped counts are incremented for skb->dev->rx_dropped
> whereas the receive counts are incremented for the vlan device
> specific private stat counter values. When the numbers are reported on
> /proc/net/dev (from where ifconfig gets the numbers), these two stat
> counters are combined together (see dev_get_stats() where rx_dropped
> is added to the device private stat numbers). So if no one is
> receiving the tagged packets, it will be reported both as received and
> dropped! I wonder whether I am analyzing it wrong or whether no one
> has noticed this before or whether this is intentional.
>
> Any  clarification will be greatly appreciated. Again, I could be
> wrong looking at the code, so please bear with me.
>
> Thanks
>
> ani
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