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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 9AEACC433DF for ; Mon, 18 May 2020 20:56:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65742207C4 for ; Mon, 18 May 2020 20:56:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589835377; bh=4N2NV+A8v59EI3FlZCS7kqqVV25Ey+qrUTEoVhSLYmM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=aU71Qkf/+dqNq0Db6tOYdl7Z2O8oTChKjzLdGOTNrlXGS4uT6LUdZ82PFwuoozbcG EqgJK20fMfHpmfNWM3vlH3lJoyOIC3tpQVzXBz9ZvWo278RqzChh5kpCX/xrB+Oa1Z yGUzAHsJsTeuVUnlnqg0ZRl3r3dpIctcSwNNoHk4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726831AbgERU4Q (ORCPT ); Mon, 18 May 2020 16:56:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:36072 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726250AbgERU4Q (ORCPT ); Mon, 18 May 2020 16:56:16 -0400 Received: from kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com (unknown [163.114.132.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4CAC120756; Mon, 18 May 2020 20:56:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589835375; bh=4N2NV+A8v59EI3FlZCS7kqqVV25Ey+qrUTEoVhSLYmM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Z1Tje6iHHbHZzT0XFlmcj0fX1H8DWEbp7xUTTYthaiNtviiKw7AAIkWJY29a9Xy0K d+ZSx2mehC7iww5XjGbzRNijTBnpqKb+yz/sypmi6gF76bNrpBYjS2yr/CXEs4MnKA 2xEtz9wJcxVd9EY7u+IqAD8d88u3TCoqv1WCLXdA= Date: Mon, 18 May 2020 13:56:13 -0700 From: Jakub Kicinski To: Vinicius Costa Gomes Cc: David Miller , olteanv@gmail.com, intel-wired-lan@lists.osuosl.org, 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 Message-ID: <20200518135613.379f6a63@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> In-Reply-To: <87wo59oyhr.fsf@intel.com> References: <20200516012948.3173993-1-vinicius.gomes@intel.com> <20200516.133739.285740119627243211.davem@davemloft.net> <20200516.151932.575795129235955389.davem@davemloft.net> <87wo59oyhr.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, 18 May 2020 12:05:04 -0700 Vinicius Costa Gomes wrote: > David Miller writes: > > From: Vladimir Oltean > > Date: Sun, 17 May 2020 00:03:39 +0300 > > > >> As to why this doesn't go to tc but to ethtool: why would it go to tc? > > > > Maybe you can't %100 duplicate the on-the-wire special format and > > whatever, but the queueing behavior ABSOLUTELY you can emulate in > > software. > > Just saying what Vladimir said in different words: the queueing behavior > is already implemented in software, by mqprio or taprio, for example. > > That is to say, if we add frame preemption support to those qdiscs all > they will do is pass the information to the driver, and that's it. They > won't be able to use that information at all. > > The mental model I have for this feature is that is more similar to the > segmentation offloads, energy efficient ethernet or auto-negotiation > than it is to a traffic shaper like CBS. Please take a look at the example from the cover letter: $ ethtool $ sudo ./ethtool --show-frame-preemption enp3s0 Frame preemption settings for enp3s0: support: supported active: active supported queues: 0xf supported queues: 0xe minimum fragment size: 68 Reading this I have no idea what 0xe is. I have to go and query TC API to see what priorities and queues that will be. Which IMHO is a strong argument that this information belongs there in the first place. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jakub Kicinski Date: Mon, 18 May 2020 13:56:13 -0700 Subject: [Intel-wired-lan] [next-queue RFC 0/4] ethtool: Add support for frame preemption In-Reply-To: <87wo59oyhr.fsf@intel.com> References: <20200516012948.3173993-1-vinicius.gomes@intel.com> <20200516.133739.285740119627243211.davem@davemloft.net> <20200516.151932.575795129235955389.davem@davemloft.net> <87wo59oyhr.fsf@intel.com> Message-ID: <20200518135613.379f6a63@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On Mon, 18 May 2020 12:05:04 -0700 Vinicius Costa Gomes wrote: > David Miller writes: > > From: Vladimir Oltean > > Date: Sun, 17 May 2020 00:03:39 +0300 > > > >> As to why this doesn't go to tc but to ethtool: why would it go to tc? > > > > Maybe you can't %100 duplicate the on-the-wire special format and > > whatever, but the queueing behavior ABSOLUTELY you can emulate in > > software. > > Just saying what Vladimir said in different words: the queueing behavior > is already implemented in software, by mqprio or taprio, for example. > > That is to say, if we add frame preemption support to those qdiscs all > they will do is pass the information to the driver, and that's it. They > won't be able to use that information at all. > > The mental model I have for this feature is that is more similar to the > segmentation offloads, energy efficient ethernet or auto-negotiation > than it is to a traffic shaper like CBS. Please take a look at the example from the cover letter: $ ethtool $ sudo ./ethtool --show-frame-preemption enp3s0 Frame preemption settings for enp3s0: support: supported active: active supported queues: 0xf supported queues: 0xe minimum fragment size: 68 Reading this I have no idea what 0xe is. I have to go and query TC API to see what priorities and queues that will be. Which IMHO is a strong argument that this information belongs there in the first place.