From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AD3CC2D0CC for ; Fri, 13 Dec 2019 22:08:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 473532073D for ; Fri, 13 Dec 2019 22:08:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726735AbfLMWIE convert rfc822-to-8bit (ORCPT ); Fri, 13 Dec 2019 17:08:04 -0500 Received: from mga01.intel.com ([192.55.52.88]:6005 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725554AbfLMWIE (ORCPT ); Fri, 13 Dec 2019 17:08:04 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Dec 2019 14:08:04 -0800 X-IronPort-AV: E=Sophos;i="5.69,311,1571727600"; d="scan'208";a="204451135" Received: from aguedesl-mac01.jf.intel.com (HELO localhost) ([10.24.12.201]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Dec 2019 14:08:03 -0800 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT In-Reply-To: <20191127094517.6255-1-Po.Liu@nxp.com> References: <20191127094517.6255-1-Po.Liu@nxp.com> Cc: "vinicius.gomes@intel.com" , "simon.horman@netronome.com" , Claudiu Manoil , Vladimir Oltean , Alexandru Marginean , Xiaoliang Yang , Roy Zang , Mingkai Hu , Jerry Huang , Leo Li , Po Liu From: Andre Guedes Subject: Re: [v1,net-next, 1/2] ethtool: add setting frame preemption of traffic classes To: "alexandru.ardelean@analog.com" , "allison@lohutok.net" , "andrew@lunn.ch" , "ayal@mellanox.com" , "davem@davemloft.net" , "f.fainelli@gmail.com" , "gregkh@linuxfoundation.org" , "hauke.mehrtens@intel.com" , "hkallweit1@gmail.com" , "jiri@mellanox.com" , "linux-kernel@vger.kernel.org" , "netdev@vger.kernel.org" , "pablo@netfilter.org" , "saeedm@mellanox.com" , "tglx@linutronix.de" , Po Liu Message-ID: <157603276975.18462.4638422874481955289@pipeline> User-Agent: alot/0.8.1 Date: Tue, 10 Dec 2019 18:52:49 -0800 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Po, Quoting Po Liu (2019-11-27 01:59:18) > IEEE Std 802.1Qbu standard defined the frame preemption of port > traffic classes. This patch introduce a method to set traffic > classes preemption. Add a parameter 'preemption' in struct > ethtool_link_settings. The value will be translated to a binary, > each bit represent a traffic class. Bit "1" means preemptable > traffic class. Bit "0" means express traffic class. MSB represent > high number traffic class. > > If hardware support the frame preemption, driver could set the > ethernet device with hw_features and features with NETIF_F_PREEMPTION > when initializing the port driver. > > User can check the feature 'tx-preemption' by command 'ethtool -k > devname'. If hareware set preemption feature. The property would > be a fixed value 'on' if hardware support the frame preemption. > Feature would show a fixed value 'off' if hardware don't support > the frame preemption. > > Command 'ethtool devname' and 'ethtool -s devname preemption N' > would show/set which traffic classes are frame preemptable. > > Port driver would implement the frame preemption in the function > get_link_ksettings() and set_link_ksettings() in the struct ethtool_ops. In an early RFC series [1], we proposed a way to support frame preemption. I'm not sure if you have considered it before implementing this other proposal based on ethtool interface so I thought it would be a good idea to bring that up to your attention, just in case. In that initial proposal, Frame Preemption feature is configured via taprio qdisc. For example: $ tc qdisc add dev IFACE parent root handle 100 taprio \ num_tc 3 \ map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \ queues 1@0 1@1 2@2 \ preemption 0 1 1 1 \ base-time 10000000 \ sched-entry S 01 300000 \ sched-entry S 02 300000 \ sched-entry S 04 400000 \ clockid CLOCK_TAI It also aligns with the gate control operations Set-And-Hold-MAC and Set-And-Release-MAC that can be set via 'sched-entry' (see Table 8.7 from 802.1Q-2018 for further details. Please share your thoughts on this. Regards, Andre