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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 155CCC433DF for ; Wed, 20 May 2020 12:52:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C45762070A for ; Wed, 20 May 2020 12:52:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=microchip.com header.i=@microchip.com header.b="JypEm3tt" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726790AbgETMwe (ORCPT ); Wed, 20 May 2020 08:52:34 -0400 Received: from esa5.microchip.iphmx.com ([216.71.150.166]:22661 "EHLO esa5.microchip.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726452AbgETMwe (ORCPT ); Wed, 20 May 2020 08:52:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=microchip.com; i=@microchip.com; q=dns/txt; s=mchp; t=1589979154; x=1621515154; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=Pmrtx5eXqbCxI6dGo1e/Adh6TjwHWVWJoZlKDTB14lY=; b=JypEm3ttTACHI28s6GWVUQZc0Lt+Lf5PidZtxV1zV+dU4ew4zj1e6cCZ gS8vBUrrhbWxhXD85anFUbK428E8xlswZqxRd50Cl+2bNT5tdBBTYgboe Jklc7djSkRfkHoKlhRZJ7WodsHSATUOx08Aef71RAGZ9iKbaBtEn8nuXo LOFf3dya7F4MhtnniNxasuQAB5GYp7kx75cua20Ry7coLTXJb5jlrq4U9 S4uKiUPDa66rZKCzJCzXofDBe9tD2hVEHYELEm8wPJSYPil5epiLoIT50 ba/vEtgU/6w8KkwpMtdw5815W3+/8w/5w8Gwn1BmJVXroambG6KzFn6We g==; IronPort-SDR: 3q/NpLbeOzsh8aoH7SJjOMpaA5WaQxNVLFey39YBgI57Y4mXWDtzJO1uzyJlOamUXxJ0ZFmIZQ vWZz7ewPjQQVyDquzdadzj1gfcKMavDFoZXm53TFuRq+h9s537CSgUBnvuWaTM8pFEfRRV5hVM bBCAZi60WJfWER5Lv/sLLFAM8RGUQrGdiN7XOJSnByVNWYJn2uu9V71HQZBL6ldtyWIvWjXlxC 3Kw4NvW+tRIO+zHMh9Bw/mkxhKJmAXlFI8S3/sEbe3vDZAtlYaUv1m3v4J/qs0QDqpCsLJ6oni 2Bk= X-IronPort-AV: E=Sophos;i="5.73,414,1583218800"; d="scan'208";a="76490592" Received: from smtpout.microchip.com (HELO email.microchip.com) ([198.175.253.82]) by esa5.microchip.iphmx.com with ESMTP/TLS/AES256-SHA256; 20 May 2020 05:52:33 -0700 Received: from chn-vm-ex02.mchp-main.com (10.10.85.144) by chn-vm-ex04.mchp-main.com (10.10.85.152) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1713.5; Wed, 20 May 2020 05:52:33 -0700 Received: from localhost (10.10.115.15) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server id 15.1.1713.5 via Frontend Transport; Wed, 20 May 2020 05:52:33 -0700 Date: Wed, 20 May 2020 14:52:32 +0200 From: Joergen Andreasen To: Vinicius Costa Gomes CC: Andre Guedes , , , , , , , Subject: Re: [next-queue RFC 0/4] ethtool: Add support for frame preemption Message-ID: <20200520125232.s3zrmlnesqjilcf6@soft-dev16> References: <20200516012948.3173993-1-vinicius.gomes@intel.com> <158992799425.36166.17850279656312622646@twxiong-mobl.amr.corp.intel.com> <87y2pnmr83.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: <87y2pnmr83.fsf@intel.com> User-Agent: NeoMutt/20171215 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The 05/19/2020 16:37, Vinicius Costa Gomes wrote: > > 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. > I think it's most intuitive to use the values for AddFragSize as described in 802.3br (N = 0, 1, 2, 3). You will anyway have to use one of these values when you want to expose the requirements of your receiver through LLDP. > > -- > Vinicius -- Joergen Andreasen, Microchip