From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH 1/2] ethdev: add function to adjust number of descriptors Date: Thu, 06 Jul 2017 01:00:57 +0200 Message-ID: <9753207.xkvjPXifed@xps> References: <1488459935-13273-2-git-send-email-arybchenko@solarflare.com> <20170525104033.43a6e02f@xeon-e3> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: Andrew Rybchenko , Sergio Gonzalez Monroy , Remy Horton , Jianfeng Tan , Declan Doherty , Ferruh Yigit , Yuanhan Liu , Maxime Coquelin , Konstantin Ananyev , Bruce Richardson , Reshma Pattan , Cristian Dumitrescu , Byron Marohn , Pablo de Lara Guarch , Pawel Wodkowski , Tomasz Kantecki , John McNamara , Daniel Mrzyglod , Roman Zhukov To: dev@dpdk.org, Stephen Hemminger Return-path: Received: from out2-smtp.messagingengine.com (out2-smtp.messagingengine.com [66.111.4.26]) by dpdk.org (Postfix) with ESMTP id 4E62E3772 for ; Thu, 6 Jul 2017 01:00:59 +0200 (CEST) In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 14/06/2017 12:37, Andrew Rybchenko: > On 05/25/2017 08:40 PM, Stephen Hemminger wrote: > > On Thu, 25 May 2017 16:57:53 +0100 > > Andrew Rybchenko wrote: > > > >> From: Roman Zhukov > >> > >> Check that numbers of Rx and Tx descriptors satisfy descriptors limits > >> from the Ethernet device information, otherwise adjust them to boundaries. > >> > >> Signed-off-by: Roman Zhukov > >> Signed-off-by: Andrew Rybchenko > > Seems like new added complexity. > > It looks like there is no more comments. > > > Why not just allow devices to take the request as a hint and truncate or pad > > as needed. > > Yes, it is possible solution. In this case rte_eth_rx_queue_info_get() > may be used > to get real values. If so, first of all it should be clearly documented > in the > rte_eth_rx_queue_setup()/rte_eth_tx_queue_setup() and > rte_eth_rx_queue_info_get()/rte_eth_tx_queue_info_get(). > However, the problem of such approach is non-obvious modification of > values specified by the ethdev API caller. Some applications use ring sizes > to estimate mbuf pool size and other resources and if real values differ > from specified (and it is not taken into account since everything happens > silently without any errors) it could be tricky to find out root cause of > possible problems. That's why we have chosen approach with extra > helper function which does the adjustment. Any more comment on this? If not, it will be applied soon. > > IMHO to be successful DPDK must have as simple as possible API for application. > > Good enough and as little more as possible. But other people seem to think > > that having the richest and most complex possible API is a good thing. I agree it is better to have a simple API. However the community process is in favor of code writers. We cannot reject a solution if there is no other solution proposed in a reasonnable timeframe.