From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jesper Dangaard Brouer <brouer@redhat.com>
Subject: Re: [bpf-next V1 PATCH 2/8] i40e: implement flush flag for
 ndo_xdp_xmit
Date: Thu, 31 May 2018 10:47:39 +0200
Message-ID: <20180531104739.3c3f6e26@redhat.com>
References: <152770312703.20510.5854417568847239931.stgit@firesoul>
        <152770324304.20510.3553783983496502887.stgit@firesoul>
        <CAPhsuW6FPfQYdwOgi_w5i6_ym6K3O50cPACR0cXAU6MDDz2Eqg@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: Networking <netdev@vger.kernel.org>,
        Daniel Borkmann <borkmann@iogearbox.net>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        John Fastabend <john.fastabend@gmail.com>,
        makita.toshiaki@lab.ntt.co.jp, brouer@redhat.com
To: Song Liu <liu.song.a23@gmail.com>
Return-path: <netdev-owner@vger.kernel.org>
Received: from mx3-rdu2.redhat.com ([66.187.233.73]:52072 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP
        id S1754040AbeEaIrp (ORCPT <rfc822;netdev@vger.kernel.org>);
        Thu, 31 May 2018 04:47:45 -0400
In-Reply-To: <CAPhsuW6FPfQYdwOgi_w5i6_ym6K3O50cPACR0cXAU6MDDz2Eqg@mail.gmail.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>

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