netdev - Re: [bpf-next V1 PATCH 2/8] i40e: implement flush flag for ndo_xdp

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Message-ID: <20180531104739.3c3f6e26@redhat.com>
Date:   Thu, 31 May 2018 10:47:39 +0200
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Song Liu <liu.song.a23@...il.com>
Cc:     Networking <netdev@...r.kernel.org>,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        John Fastabend <john.fastabend@...il.com>,
        makita.toshiaki@....ntt.co.jp, brouer@...hat.com
Subject: Re: [bpf-next V1 PATCH 2/8] i40e: implement flush flag for
 ndo_xdp_xmit

On Wed, 30 May 2018 14:58:16 -0700 Song Liu <liu.song.a23@...il.com> wrote:

> > @@ -3699,6 +3699,9 @@ int i40e_xdp_xmit(struct net_device *dev, int n, struct xdp_frame **frames,
> >                 }
> >         }
> >
> > +       if (unlikely(flags & XDP_XMIT_FLUSH))
> > +               i40e_xdp_ring_update_tail(vsi->xdp_rings[queue_index]);
> > +
> >         return n - drops;  
> 
> Do we still flush when drops > 0?

Yes, just as before. Even if all frames are dropped, then it's allowed
to update the tail.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer