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,URIBL_BLOCKED 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 A22CDC433DF for ; Tue, 19 May 2020 23:37:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7AA3920674 for ; Tue, 19 May 2020 23:37:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728085AbgESXhS (ORCPT ); Tue, 19 May 2020 19:37:18 -0400 Received: from mga18.intel.com ([134.134.136.126]:31177 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726178AbgESXhS (ORCPT ); Tue, 19 May 2020 19:37:18 -0400 IronPort-SDR: BE+O8UpT331NylZepVOzFraLOwBoEbJBvaTaHGPFn6Xr69HAXZiZi1/ZCdWu2+LbPbwucrK39b /JQVbRG74tXA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 May 2020 16:37:17 -0700 IronPort-SDR: efCpJZMQHt0EarEpHhcIdrY++jdSzf6UO8hAsrlDSoHhaJEIp/v3IWrIJ+4Hpf2pW9+ERbCb6z 8uoY6XsoCpUA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,411,1583222400"; d="scan'208";a="466318416" Received: from stputhen-mobl1.amr.corp.intel.com (HELO ellie) ([10.209.5.127]) by fmsmga006.fm.intel.com with ESMTP; 19 May 2020 16:37:16 -0700 From: Vinicius Costa Gomes To: Andre Guedes , intel-wired-lan@lists.osuosl.org Cc: jeffrey.t.kirsher@intel.com, netdev@vger.kernel.org, vladimir.oltean@nxp.com, po.liu@nxp.com, m-karicheri2@ti.com, Jose.Abreu@synopsys.com Subject: Re: [next-queue RFC 0/4] ethtool: Add support for frame preemption In-Reply-To: <158992799425.36166.17850279656312622646@twxiong-mobl.amr.corp.intel.com> References: <20200516012948.3173993-1-vinicius.gomes@intel.com> <158992799425.36166.17850279656312622646@twxiong-mobl.amr.corp.intel.com> Date: Tue, 19 May 2020 16:37:16 -0700 Message-ID: <87y2pnmr83.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Andre Guedes writes: > Hi, > > Quoting Vinicius Costa Gomes (2020-05-15 18:29:44) >> One example, for retrieving and setting the configuration: >> >> $ ethtool $ sudo ./ethtool --show-frame-preemption enp3s0 >> Frame preemption settings for enp3s0: >> support: supported >> active: active > > IIUC the code in patch 2, 'active' is the actual configuration knob that > enables or disables the FP functionality on the NIC. > > That sounded a bit confusing to me since the spec uses the term 'active' to > indicate FP is currently enabled at both ends, and it is a read-only > information (see 12.30.1.4 from IEEE 802.1Q-2018). Maybe if we called this > 'enabled' it would be more clear. Good point. Will rename this to "enabled". > >> supported queues: 0xf >> supported queues: 0xe >> minimum fragment size: 68 > > I'm assuming this is the configuration knob for the minimal non-final fragment > defined in 802.3br. > > My understanding from the specs is that this value must be a multiple from 64 > and cannot assume arbitrary values like shown here. See 99.4.7.3 from IEEE > 802.3 and Note 1 in S.2 from IEEE 802.1Q. In the previous discussion about FP, > we had this as a multiplier factor, not absolute value. I thought that exposing this as "(1 + N)*64" (with 0 <= N <= 3) that it was more related to what's exposed via LLDP than the actual capabilities of the hardware. And for the hardware I have actually the values supported are: (1 + N)*64 + 4 (for N = 0, 1, 2, 3). So I thought I was better to let the driver decide what values are acceptable. This is a good question for people working with other hardware. -- Vinicius From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vinicius Costa Gomes Date: Tue, 19 May 2020 16:37:16 -0700 Subject: [Intel-wired-lan] [next-queue RFC 0/4] ethtool: Add support for frame preemption In-Reply-To: <158992799425.36166.17850279656312622646@twxiong-mobl.amr.corp.intel.com> References: <20200516012948.3173993-1-vinicius.gomes@intel.com> <158992799425.36166.17850279656312622646@twxiong-mobl.amr.corp.intel.com> Message-ID: <87y2pnmr83.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: Andre Guedes writes: > Hi, > > Quoting Vinicius Costa Gomes (2020-05-15 18:29:44) >> One example, for retrieving and setting the configuration: >> >> $ ethtool $ sudo ./ethtool --show-frame-preemption enp3s0 >> Frame preemption settings for enp3s0: >> support: supported >> active: active > > IIUC the code in patch 2, 'active' is the actual configuration knob that > enables or disables the FP functionality on the NIC. > > That sounded a bit confusing to me since the spec uses the term 'active' to > indicate FP is currently enabled at both ends, and it is a read-only > information (see 12.30.1.4 from IEEE 802.1Q-2018). Maybe if we called this > 'enabled' it would be more clear. Good point. Will rename this to "enabled". > >> supported queues: 0xf >> supported queues: 0xe >> minimum fragment size: 68 > > I'm assuming this is the configuration knob for the minimal non-final fragment > defined in 802.3br. > > My understanding from the specs is that this value must be a multiple from 64 > and cannot assume arbitrary values like shown here. See 99.4.7.3 from IEEE > 802.3 and Note 1 in S.2 from IEEE 802.1Q. In the previous discussion about FP, > we had this as a multiplier factor, not absolute value. I thought that exposing this as "(1 + N)*64" (with 0 <= N <= 3) that it was more related to what's exposed via LLDP than the actual capabilities of the hardware. And for the hardware I have actually the values supported are: (1 + N)*64 + 4 (for N = 0, 1, 2, 3). So I thought I was better to let the driver decide what values are acceptable. This is a good question for people working with other hardware. -- Vinicius