From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yongseok Koh <yskoh@mellanox.com>
Subject: Re: Requirement of minimum Rx burst size for PMDs
Date: Fri, 20 Oct 2017 09:59:58 -0700
Message-ID: <20171020165957.GA17026@yongseok-MBP.local>
References: <BD4E5B5E-6CDE-4180-8040-58027CF32897@mellanox.com>
 <df9493e1-6df4-0219-b211-ff295bb1191e@solarflare.com>
 <20171020115823.GA21216@bricha3-MOBL3.ger.corp.intel.com>
 <56be56b2-092a-ddc1-85ef-6e14065382bd@solarflare.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: Bruce Richardson <bruce.richardson@intel.com>,
 "dev@dpdk.org" <dev@dpdk.org>
To: Andrew Rybchenko <arybchenko@solarflare.com>
Return-path: <dev-bounces@dpdk.org>
Received: from EUR02-AM5-obe.outbound.protection.outlook.com
 (mail-eopbgr00044.outbound.protection.outlook.com [40.107.0.44])
 by dpdk.org (Postfix) with ESMTP id 7A6162A6C
 for <dev@dpdk.org>; Fri, 20 Oct 2017 19:00:11 +0200 (CEST)
Content-Disposition: inline
In-Reply-To: <56be56b2-092a-ddc1-85ef-6e14065382bd@solarflare.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 Fri, Oct 20, 2017 at 03:23:10PM +0300, Andrew Rybchenko wrote:
> On 10/20/2017 02:58 PM, Bruce Richardson wrote:
> > On Fri, Oct 20, 2017 at 01:07:17PM +0300, Andrew Rybchenko wrote:
> > > On 10/20/2017 04:18 AM, Yongseok Koh wrote:
> > > > Therefore, how about adding min_rx/tx_burst_sz in struct rte_eth_dev_info and
> > > > have PMDs fill it in on dev_ops->dev_infos_get() so as to make apps comply with
> > > > it.
> > > Just for my understand, what should happen if application wants to send only
> > > one packet? 5 packets? 33? 35?
> > I actually think there is a mistake in the original mails. At least for
> > Intel PMDs there is no restriction on min TX burst sizes in any code
> > path. The vector RX on the other hand does require a minimum number of empty
> > buffers to be passed to it, so you need to request no fewer than 4
> > packets in a burst. If only one packet is available that will still be
> > returned to you, but you must request at least 4
> 
> I see. The thread subject says Rx, but Tx (min_tx_burst_sz) is mentioned
> above.
> If Tx is mentioned by mistake, it is clear now.

Oops, Tx was mistakenly mentioned. Neither Intel nor Mellanox PMD has such
restriction on Tx burst size.

Will come up with a patch for it soon.

Thanks,
Yongseok