From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tiwei Bie <tiwei.bie@intel.com>
Subject: Re: [PATCH 1/5] net/virtio: fix vector Rx break caused
 by rxq flushing
Date: Fri, 8 Dec 2017 10:30:34 +0800
Message-ID: <20171208023034.4f5u3fujmupraaia@debian-xvivbkq>
References: <20171207053059.19487-1-tiwei.bie@intel.com>
 <20171207053059.19487-2-tiwei.bie@intel.com>
 <9407e2ce-8b2b-9a9d-a493-1757609184a9@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Cc: yliu@fridaylinux.org, maxime.coquelin@redhat.com, dev@dpdk.org,
 antonio.fischetti@intel.com, stable@dpdk.org,
 "Kavanagh, Mark B" <mark.b.kavanagh@intel.com>
To: Kevin Traynor <ktraynor@redhat.com>
Return-path: <dev-bounces@dpdk.org>
Content-Disposition: inline
In-Reply-To: <9407e2ce-8b2b-9a9d-a493-1757609184a9@redhat.com>
List-Id: DPDK patches and discussions <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Thu, Dec 07, 2017 at 04:00:57PM +0000, Kevin Traynor wrote:
> On 12/07/2017 05:30 AM, Tiwei Bie wrote:
> > The vector Rx will be broken if backend has consumed all
> > the descs in the avail ring before the device is started.
> > Because in current implementation, vector Rx will return
> > immediately without refilling the avail ring if the used
> > ring is empty. So we have to refill the avail ring after
> > flushing the elements in the used ring for vector Rx.
> > 
> > Besides, vector Rx has a different ring layout assumption
> > and mbuf management. So we need to handle it differently.
> > 
> 
> Hi Tiwei, does the issue only occur with the vector rx? How about if the
> simple rx is used because VIRTIO_NET_F_MRG_RXBUF is set?

Hi Kevin,

Yes, you are right! The issue only occurs with the vector
Rx. The vector Rx (i.e. the simple Rx) won't be used if
VIRTIO_NET_F_MRG_RXBUF is set.

Best regards,
Tiwei Bie