From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Subject: Re: [PATCH 2/4] virtio: introduce
 RTE_LIBRTE_VIRTIO_INC_VECTOR
Date: Wed, 29 Jun 2016 17:10:31 +0530
Message-ID: <20160629114030.GC5301@localhost.localdomain>
References: <1467028448-8914-1-git-send-email-jerin.jacob@caviumnetworks.com>
 <3436400.asiby3BQPB@xps13>
 <20160629111848.GA5301@localhost.localdomain>
 <6020070.DOjM99b0E6@xps13>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Cc: <dev@dpdk.org>, <bruce.richardson@intel.com>, <jianbo.liu@linaro.org>,
 <huawei.xie@intel.com>, <yuanhan.liu@linux.intel.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
Return-path: <dev-bounces@dpdk.org>
Received: from na01-by2-obe.outbound.protection.outlook.com
 (mail-by2on0084.outbound.protection.outlook.com [207.46.100.84])
 by dpdk.org (Postfix) with ESMTP id 6E14C2BA7
 for <dev@dpdk.org>; Wed, 29 Jun 2016 13:40:51 +0200 (CEST)
Content-Disposition: inline
In-Reply-To: <6020070.DOjM99b0E6@xps13>
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 Wed, Jun 29, 2016 at 01:25:35PM +0200, Thomas Monjalon wrote:
> 2016-06-29 16:48, Jerin Jacob:
> > On Mon, Jun 27, 2016 at 04:59:42PM +0200, Thomas Monjalon wrote:
> > > 2016-06-27 20:18, Jerin Jacob:
> > > > On Mon, Jun 27, 2016 at 04:19:57PM +0200, Thomas Monjalon wrote:
> > > > > 2016-06-27 17:24, Jerin Jacob:
> > > > > > --- a/config/common_base
> > > > > > +++ b/config/common_base
> > > > > > @@ -267,6 +267,7 @@ CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_RX=n
> > > > > >  CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_TX=n
> > > > > >  CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_DRIVER=n
> > > > > >  CONFIG_RTE_LIBRTE_VIRTIO_DEBUG_DUMP=n
> > > > > > +CONFIG_RTE_LIBRTE_VIRTIO_INC_VECTOR=y
> > > > > 
> > > > > I don't remember what means INC_VECTOR?
> > > > > Why a config option is needed for vector implementations?
> > > > 
> > > > I thought of adding additional configuration option(INC_VECTOR) _apart_ from
> > > > cpu flag based scheme in the patch because even though if a given platform
> > > > has cpu instruction support, in some platforms scalar version may
> > > > perform well wrt vector version(based on instruction latency, emulation required or not
> > > > etc). So a top level flag INC_VECTOR, can override the vector selection
> > > > for a given platform if required.
> > > 
> > > Isn't it a runtime driver option needed to disable vector virtio?
> > > 
> > > > Regarding INC_VECTOR(INC in vector configuration name, I have no idea, I
> > > > followed the existing flags)
> > > > $ grep "INC_VECTOR" config/common_base
> > > > CONFIG_RTE_IXGBE_INC_VECTOR=y
> > > > CONFIG_RTE_LIBRTE_I40E_INC_VECTOR=y
> > > > CONFIG_RTE_LIBRTE_FM10K_INC_VECTOR=y
> > > 
> > > If the flag is really needed I would suggest VIRTIO_VECTOR.
> > 
> > OK I will change to VIRTIO_VECTOR
> 
> I would prefer a runtime option.

OK

The platform I test their was NO need for additional VIRTIO_VECTOR
configuration as NEON versions outperforms than scalar version.

I thought of adding this option to override for any platform if it need
to accommodate such platform differences NEON vs scalar versions.

I will change completely to run-time detection based on cpuflags for IA and ARM.
Any objections?

Jerin