linux-kernel - Re: [PATCH net-next 2/2] virtio-net: simplify XDP handling in small buffer

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Message-ID: <5c20a958-55c6-5a5f-c0e9-dc6f7c0e4db5@redhat.com>
Date:   Thu, 1 Mar 2018 17:24:35 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     mst@...hat.com, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        john.fastabend@...il.com
Subject: Re: [PATCH net-next 2/2] virtio-net: simplify XDP handling in small
 buffer



On 2018年03月01日 17:15, Jesper Dangaard Brouer wrote:
> On Thu, 1 Mar 2018 16:49:24 +0800
> Jason Wang <jasowang@...hat.com> wrote:
>
>>> 2. This can easily cause out-of-order packets.
>> I may miss something, but it looks to me packets were still delivered
>> in order? Or you mean the packets that was dropped by cpumap?
> No. Packets can now travel two code paths to the egress device. (1) XDP
> native via ndp_xdp_xmit via direct delivery into a lockfree/dedicated
> TX queue, (2) via normal network stack which can involve being queue in
> a qdisc.  Do you see the possibility of the reorder now?
>

I see, thanks. But consider this could only happen for first few 
packets, not sure it was worth to worry about it.

Thanks