netdev - Re: [PATCH RFC net-next] net: vlan/macvlan: count packets properly with gso

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Date:   Thu, 29 Nov 2018 13:43:15 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "Duyck, Alexander H" <alexander.h.duyck@...el.com>,
        "dbanerje@...mai.com" <dbanerje@...mai.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH RFC net-next] net: vlan/macvlan: count packets properly
 with gso



On 11/29/2018 01:13 PM, Duyck, Alexander H wrote:

> Instead of just checking for the max it might make more sense to do a
> check using skb_is_gso, and then if true use gso_segs, otherwise just
> default to 1.
> 
> Also your bytes are going to be totally messed up as well since the
> headers are trimmed in the GSO frames. It might be worthwhile to just
> have a branch based on skb_is_gso that sets the packets and bytes based
> on the GSO values, and one that sets it for the default case.
> 
Note that __dev_queue_xmit() is already doing that, no need
to re-implement in each driver.

It calls qdisc_pkt_len_init(), meaning that drivers can use 
qdisc_skb_cb(skb)->pkt_len instead of skb->len

(Qdisc layers should not modify qdisc_skb_cb(skb)->pkt_len )