netdev - Re: [PATCH net] virtio_net: Account for tx bytes and packets on sending xdp

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Date:   Thu, 31 Jan 2019 09:45:23 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     mst@...hat.com
Cc:     makita.toshiaki@....ntt.co.jp, jasowang@...hat.com,
        netdev@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        dsahern@...il.com, hawk@...nel.org
Subject: Re: [PATCH net] virtio_net: Account for tx bytes and packets on
 sending xdp_frames

From: "Michael S. Tsirkin" <mst@...hat.com>
Date: Thu, 31 Jan 2019 10:25:17 -0500

> On Thu, Jan 31, 2019 at 08:40:30PM +0900, Toshiaki Makita wrote:
>> Previously virtnet_xdp_xmit() did not account for device tx counters,
>> which caused confusions.
>> To be consistent with SKBs, account them on freeing xdp_frames.
>> 
>> Reported-by: David Ahern <dsahern@...il.com>
>> Signed-off-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>
> 
> Well we count them on receive so I guess it makes sense for consistency
> 
> Acked-by: Michael S. Tsirkin <mst@...hat.com>
> 
> however, I really wonder whether adding more and more standard net stack
> things like this will end up costing most of XDP its speed.
> 
> Should we instead make sure *not* to account XDP packets
> in any counters at all? XDP programs can use maps
> to do their own counting...

This has been definitely a discussion point, and something we should
develop a clear, strong, policy on.

David, Jesper, care to chime in where we ended up in that last thread
discussion this?