From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH 3/4] virtio: use indirect ring elements
Date: Sun, 6 Sep 2015 11:42:02 -0700
Message-ID: <20150906114202.634c8602@urahara>
References: <1441400308-5725-1-git-send-email-stephen@networkplumber.org>
 <1441400308-5725-4-git-send-email-stephen@networkplumber.org>
 <F52918179C57134FAEC9EA62FA2F962511CFDA18@shsmsx102.ccr.corp.intel.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: "dev@dpdk.org" <dev@dpdk.org>
To: "Ouyang, Changchun" <changchun.ouyang@intel.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-pa0-f48.google.com (mail-pa0-f48.google.com
 [209.85.220.48]) by dpdk.org (Postfix) with ESMTP id 9B39B8EA0
 for <dev@dpdk.org>; Sun,  6 Sep 2015 20:41:51 +0200 (CEST)
Received: by padhy16 with SMTP id hy16so71328764pad.1
 for <dev@dpdk.org>; Sun, 06 Sep 2015 11:41:51 -0700 (PDT)
In-Reply-To: <F52918179C57134FAEC9EA62FA2F962511CFDA18@shsmsx102.ccr.corp.intel.com>
List-Id: patches and discussions about DPDK <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 Sun, 6 Sep 2015 08:36:10 +0000
"Ouyang, Changchun" <changchun.ouyang@intel.com> wrote:

> > -----Original Message-----
> > From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> > Sent: Saturday, September 5, 2015 4:58 AM
> > To: Xie, Huawei; Ouyang, Changchun
> > Cc: dev@dpdk.org; Stephen Hemminger
> > Subject: [PATCH 3/4] virtio: use indirect ring elements
> > 
> > The virtio ring in QEMU/KVM is usually limited to 256 entries and the normal
> > way that virtio driver was queuing mbufs required nsegs + 1 ring elements.
> > By using the indirect ring element feature if available, each packet will take
> > only one ring slot even for multi-segment packets.
> > 
> > Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> > ---
> >  drivers/net/virtio/virtio_ethdev.c | 11 +++++---
> > drivers/net/virtio/virtio_ethdev.h |  3 ++-
> >  drivers/net/virtio/virtio_rxtx.c   | 51 ++++++++++++++++++++++++++++++-
> > -------
> >  drivers/net/virtio/virtqueue.h     |  8 ++++++
> >  4 files changed, 57 insertions(+), 16 deletions(-)
> > 
> > diff --git a/drivers/net/virtio/virtio_ethdev.c
> > b/drivers/net/virtio/virtio_ethdev.c
> > index 465d3cd..bcfb87b 100644
> > --- a/drivers/net/virtio/virtio_ethdev.c
> > +++ b/drivers/net/virtio/virtio_ethdev.c
> > @@ -359,12 +359,15 @@ int virtio_dev_queue_setup(struct rte_eth_dev
> > *dev,
> >  	if (queue_type == VTNET_TQ) {  
> 
> Do we also need implement indirect ring elements for RX path?

No. Look at Linux driver, indirect elements are never passed to RX driver.