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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C34DC43334 for ; Tue, 5 Jul 2022 22:45:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231184AbiGEWpV (ORCPT ); Tue, 5 Jul 2022 18:45:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229486AbiGEWpV (ORCPT ); Tue, 5 Jul 2022 18:45:21 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8694013D43 for ; Tue, 5 Jul 2022 15:45:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1657061120; x=1688597120; h=from:to:subject:in-reply-to:references:date:message-id: mime-version; bh=xjmeVmjIx/Y6eYkPpz+rpBanJPJnMJQIG7fRtO1ZKXg=; b=hXjX0Hb8HddMW9CZ12nHUXqgiCcRP6U3y1p6ksdteBHLjZFR8Xq7INuF tkyXsIAuICAai88rBXFqlaHLm+EmRRVCOf90YXRZznDjzjl29jjSbK8QJ aZWPY6Fz/ouNDoOP4tGvoeu7OvRTgGMKzZiUTCmG7gKV7JCqwHyVOC+UT gykarZsWuH0Wc7A/4CBkayMsC3ZWzUXBvPSw6YcldFjDydxCsO9Mjaakz doVDNRcMDVyBgM+lvwTT44MPwkDnoc0TjlJEuiQcMsSOMAT2WeoBf0bfx eGZnSNB+Lo7cBNJSj3FByC8uXdAOj66RZ64Fz/DMh0Fd9K5HNZcvCYnha Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10399"; a="284283870" X-IronPort-AV: E=Sophos;i="5.92,248,1650956400"; d="scan'208";a="284283870" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jul 2022 15:45:20 -0700 X-IronPort-AV: E=Sophos;i="5.92,248,1650956400"; d="scan'208";a="597447147" Received: from vcostago-mobl3.jf.intel.com (HELO vcostago-mobl3) ([10.24.14.91]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Jul 2022 15:45:19 -0700 From: Vinicius Costa Gomes To: Ascend~ <1176303504@qq.com>, netdev , shemminger Subject: Re: linux manual question consultation In-Reply-To: References: Date: Tue, 05 Jul 2022 15:45:17 -0700 Message-ID: <87k08r6uwy.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, "Ascend~" <1176303504@qq.com> writes: > Hello, I am studying the linux manual, and I don't understand something, I don't know if it is written wrong, can you provide a little help? Questions are as follows: > URL:https://www.mankier.com/8/tc-taprio > I see "the txtime offload mode in taprio" gives an example like this: > > # tc qdisc replace dev eth0 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@0 1@0 \ base-time 1528743495910289987 \ sched-entry S 01 300000 \ sched-entry S 02 300000 \ sched-entry S 04 400000 \ flags 0x1 \ txtime-delay 200000 \ clockid CLOCK_TAI # tc qdisc replace dev $IFACE parent 100:1 etf skip_skb_check \ offload delta 200000 clockid CLOCK_TAI > > Why is count@offset written as queues 1@0 1@0 1@0 here? A bit of background, txtime assisted mode is an implementation of the enhancements for scheduled traffic state machines from IEEE 802.1Q-2018 using the "LaunchTime" (be able to specify a "precise" transmission time of a packet) feature, using the ETF qdisc. The current implementation has a limitation in the sense that it is only able to use a single HW transmission queue, that's why, all traffic is directed to a single HW queue. > Is it mapping all traffic traffic types to queue 0? Yes. > If it is understood, is it meaningless to set "sched-entry"? If it is > not understood this way, can you help me explain it? Thank you very > much! It's not meaningless, the traffic scheduling is done in terms of "traffic classes" (the bit mask in 'sched-entry' are in reference to traffic classes), "only" when sending packets down to the driver/NIC that we use a single queue. Note that this limitation is not a "hard" one, it most probably can be solved with some time and better data structures in the taprio side. Hope this answers your questions. Cheers, -- Vinicius