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[ { "id": 115373, "web_url": "https://patches.dpdk.org/comment/115373/", "msgid": "<20200707143251.GJ5869@platinum>", "list_archive_url": "https://inbox.dpdk.org/dev/20200707143251.GJ5869@platinum", "date": "2020-07-07T14:32:51", "subject": "Re: [dpdk-dev] [PATCH v3 1/2] mbuf: introduce accurate packet Tx\n\tscheduling", "submitter": { "id": 8, "url": "https://patches.dpdk.org/api/people/8/?format=api", "name": "Olivier Matz", "email": "olivier.matz@6wind.com" }, "content": "On Tue, Jul 07, 2020 at 01:08:02PM +0000, Viacheslav Ovsiienko wrote:\n> There is the requirement on some networks for precise traffic timing\n> management. The ability to send (and, generally speaking, receive)\n> the packets at the very precisely specified moment of time provides\n> the opportunity to support the connections with Time Division\n> Multiplexing using the contemporary general purpose NIC without involving\n> an auxiliary hardware. For example, the supporting of O-RAN Fronthaul\n> interface is one of the promising features for potentially usage of the\n> precise time management for the egress packets.\n> \n> The main objective of this RFC is to specify the way how applications\n> can provide the moment of time at what the packet transmission must be\n> started and to describe in preliminary the supporting this feature from\n> mlx5 PMD side.\n> \n> The new dynamic timestamp field is proposed, it provides some timing\n> information, the units and time references (initial phase) are not\n> explicitly defined but are maintained always the same for a given port.\n> Some devices allow to query rte_eth_read_clock() that will return\n> the current device timestamp. The dynamic timestamp flag tells whether\n> the field contains actual timestamp value. For the packets being sent\n> this value can be used by PMD to schedule packet sending.\n> \n> After PKT_RX_TIMESTAMP flag and fixed timestamp field deprecation\n> and obsoleting, these dynamic flag and field will be used to manage\n> the timestamps on receiving datapath as well.\n> \n> When PMD sees the \"rte_dynfield_timestamp\" set on the packet being sent\n> it tries to synchronize the time of packet appearing on the wire with\n> the specified packet timestamp. If the specified one is in the past it\n> should be ignored, if one is in the distant future it should be capped\n> with some reasonable value (in range of seconds). These specific cases\n> (\"too late\" and \"distant future\") can be optionally reported via\n> device xstats to assist applications to detect the time-related\n> problems.\n> \n> There is no any packet reordering according timestamps is supposed,\n> neither within packet burst, nor between packets, it is an entirely\n> application responsibility to generate packets and its timestamps\n> in desired order. The timestamps can be put only in the first packet\n> in the burst providing the entire burst scheduling.\n> \n> PMD reports the ability to synchronize packet sending on timestamp\n> with new offload flag:\n> \n> This is palliative and is going to be replaced with new eth_dev API\n> about reporting/managing the supported dynamic flags and its related\n> features. This API would break ABI compatibility and can't be introduced\n> at the moment, so is postponed to 20.11.\n> \n> For testing purposes it is proposed to update testpmd \"txonly\"\n> forwarding mode routine. With this update testpmd application generates\n> the packets and sets the dynamic timestamps according to specified time\n> pattern if it sees the \"rte_dynfield_timestamp\" is registered.\n> \n> The new testpmd command is proposed to configure sending pattern:\n> \n> set tx_times <burst_gap>,<intra_gap>\n> \n> <intra_gap> - the delay between the packets within the burst\n> specified in the device clock units. The number\n> of packets in the burst is defined by txburst parameter\n> \n> <burst_gap> - the delay between the bursts in the device clock units\n> \n> As the result the bursts of packet will be transmitted with specific\n> delays between the packets within the burst and specific delay between\n> the bursts. The rte_eth_get_clock is supposed to be engaged to get the\n> current device clock value and provide the reference for the timestamps.\n> \n> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>\n> ---\n> lib/librte_ethdev/rte_ethdev.c | 1 +\n> lib/librte_ethdev/rte_ethdev.h | 4 ++++\n> lib/librte_mbuf/rte_mbuf_dyn.h | 32 ++++++++++++++++++++++++++++++++\n> 3 files changed, 37 insertions(+)\n> \n> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c\n> index 8e10a6f..02157d5 100644\n> --- a/lib/librte_ethdev/rte_ethdev.c\n> +++ b/lib/librte_ethdev/rte_ethdev.c\n> @@ -162,6 +162,7 @@ struct rte_eth_xstats_name_off {\n> \tRTE_TX_OFFLOAD_BIT2STR(UDP_TNL_TSO),\n> \tRTE_TX_OFFLOAD_BIT2STR(IP_TNL_TSO),\n> \tRTE_TX_OFFLOAD_BIT2STR(OUTER_UDP_CKSUM),\n> +\tRTE_TX_OFFLOAD_BIT2STR(SEND_ON_TIMESTAMP),\n> };\n> \n> #undef RTE_TX_OFFLOAD_BIT2STR\n> diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h\n> index a49242b..6f6454c 100644\n> --- a/lib/librte_ethdev/rte_ethdev.h\n> +++ b/lib/librte_ethdev/rte_ethdev.h\n> @@ -1178,6 +1178,10 @@ struct rte_eth_conf {\n> /** Device supports outer UDP checksum */\n> #define DEV_TX_OFFLOAD_OUTER_UDP_CKSUM 0x00100000\n> \n> +/** Device supports send on timestamp */\n> +#define DEV_TX_OFFLOAD_SEND_ON_TIMESTAMP 0x00200000\n> +\n> +\n> #define RTE_ETH_DEV_CAPA_RUNTIME_RX_QUEUE_SETUP 0x00000001\n> /**< Device supports Rx queue setup after device started*/\n> #define RTE_ETH_DEV_CAPA_RUNTIME_TX_QUEUE_SETUP 0x00000002\n> diff --git a/lib/librte_mbuf/rte_mbuf_dyn.h b/lib/librte_mbuf/rte_mbuf_dyn.h\n> index 96c3631..5b2f3da 100644\n> --- a/lib/librte_mbuf/rte_mbuf_dyn.h\n> +++ b/lib/librte_mbuf/rte_mbuf_dyn.h\n> @@ -250,4 +250,36 @@ int rte_mbuf_dynflag_lookup(const char *name,\n> #define RTE_MBUF_DYNFIELD_METADATA_NAME \"rte_flow_dynfield_metadata\"\n> #define RTE_MBUF_DYNFLAG_METADATA_NAME \"rte_flow_dynflag_metadata\"\n> \n> +/**\n> + * The timestamp dynamic field provides some timing information, the\n> + * units and time references (initial phase) are not explicitly defined\n> + * but are maintained always the same for a given port. Some devices allow\n> + * to query rte_eth_read_clock() that will return the current device\n> + * timestamp. The dynamic Tx timestamp flag tells whether the field contains\n> + * actual timestamp value. For the packets being sent this value can be\n> + * used by PMD to schedule packet sending.\n> + *\n> + * After PKT_RX_TIMESTAMP flag and fixed timestamp field deprecation\n> + * and obsoleting, the dedicated Rx timestamp flag is supposed to be\n> + * introduced and the shared timestamp field will be used to handle the\n> + * timestamps on receiving datapath as well. Having the dedicated flags\n> + * for Rx/Tx timstamps allows applications not to perform explicit flags\n> + * reset on forwarding and not to promote received timestamps to the\n> + * transmitting datapath by default.\n> + *\n> + * When PMD sees the RTE_MBUF_DYNFLAG_TX_TIMESTAMP_NAME flag set on the\n> + * packet being sent it tries to synchronize the time of packet appearing\n> + * on the wire with the specified packet timestamp. If the specified one\n> + * is in the past it should be ignored, if one is in the distant future\n> + * it should be capped with some reasonable value (in range of seconds).\n> + *\n> + * There is no any packet reordering according timestamps is supposed,\n\nI think there is a typo here\n\n> + * neither within packet burst, nor between packets, it is an entirely\n> + * application responsibility to generate packets and its timestamps in\n> + * desired order. The timestamps might be put only in the first packet in\n> + * the burst providing the entire burst scheduling.\n> + */\n> +#define RTE_MBUF_DYNFIELD_TIMESTAMP_NAME \"rte_dynfield_timestamp\"\n> +#define RTE_MBUF_DYNFLAG_TX_TIMESTAMP_NAME \"rte_dynflag_tx_timestamp\"\n\nIs it possible to split the comment, to document both\nRTE_MBUF_DYNFIELD_TIMESTAMP_NAME and RTE_MBUF_DYNFLAG_TX_TIMESTAMP_NAME ? I\ndidn't try to generate the documentation, but I think, like this, that\nRTE_MBUF_DYNFLAG_TX_TIMESTAMP_NAME will be undocumented.\n\nApart from that, it looks good to me.\n\n\n> +\n> #endif\n> -- \n> 1.8.3.1\n>", "headers": { "Return-Path": "<dev-bounces@dpdk.org>", "X-Original-To": "patchwork@inbox.dpdk.org", "Delivered-To": "patchwork@inbox.dpdk.org", "Received": [ "from dpdk.org (dpdk.org [92.243.14.124])\n\tby inbox.dpdk.org (Postfix) with ESMTP id 3B691A00BE;\n\tTue, 7 Jul 2020 16:32:56 +0200 (CEST)", "from [92.243.14.124] (localhost [127.0.0.1])\n\tby dpdk.org (Postfix) with ESMTP id 21D501DD8D;\n\tTue, 7 Jul 2020 16:32:55 +0200 (CEST)", "from mail-wr1-f68.google.com (mail-wr1-f68.google.com\n [209.85.221.68]) by dpdk.org (Postfix) with ESMTP id 60A371D597\n for <dev@dpdk.org>; Tue, 7 Jul 2020 16:32:53 +0200 (CEST)", "by mail-wr1-f68.google.com with SMTP id f7so42366824wrw.1\n for <dev@dpdk.org>; Tue, 07 Jul 2020 07:32:53 -0700 (PDT)", "from 6wind.com\n (2a01cb0c0005a600345636f7e65ed1a0.ipv6.abo.wanadoo.fr.\n [2a01:cb0c:5:a600:3456:36f7:e65e:d1a0])\n by smtp.gmail.com with ESMTPSA id r1sm1174110wrt.73.2020.07.07.07.32.52\n (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n Tue, 07 Jul 2020 07:32:52 -0700 (PDT)" ], "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed; d=6wind.com; s=google;\n h=date:from:to:cc:subject:message-id:references:mime-version\n :content-disposition:in-reply-to:user-agent;\n bh=ztDyJaZ+gpf5++1Gb3NpDyjVPhxx0G8qNhPNu8VXyVU=;\n b=V1HD5OwsDjgOBTvEj2k0C+ybGsX26UmJQfo9u5uA1AVhOoTzBOgIPRF6ewfIdkMLlD\n AaP9HrYRaBTGaiNYiKfSPUJaiqsiYwUbMtgZam3C5ar1gbgS+Aqkp7t1K7qpNRfozAz7\n bvMitazwuznyDQ0c76MQzh56hWdMl5iz98gf7zlwpmPr1W+S1vThcGpEYdRhDu9qo+T0\n 6t3aY7IAtRdfR8BfDPDgg0yKi6GRLpQxEk4yEX6QXuJqnM3cwSNd23cNoxJwD0D7FtQx\n YIOkgmdaN6It/oTguhD1psF5FmWynOBPs3noyc58+VTWsXwAof8vyGoyjm+4EvqLWgY4\n InpQ==", "X-Google-DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20161025;\n h=x-gm-message-state:date:from:to:cc:subject:message-id:references\n :mime-version:content-disposition:in-reply-to:user-agent;\n bh=ztDyJaZ+gpf5++1Gb3NpDyjVPhxx0G8qNhPNu8VXyVU=;\n b=oxs/9JrxP7uX3ZpgttWcEaMv8sccOt3lPawyFOnBYPfrKZXS+UDqQgqWtTwr0p4oXD\n oclp7PoXhRt9DW0xNBPnDIUzug0zOgkqgSBaPoFG8KB3WG502F/V62iERFUdQQ7EotsA\n bW+5dG9GsJp+SWrKGoioJZ5a7NVOkHJhRMlnoGCS/C0xlwUQjeu0DP9IC+k2/bVLvGDL\n iurZb9MsAPJoFbZNo9+IDJkcpE6mwV5u97ibO6Q6IMBaWI5WWQSyWmQ66V7MkaNO20ya\n WkfT8YvNaG96z3DO/qZJHeIYyLqbqR8h/jTS6NaLSxY7JCl+zCxWxqfqzQtbulET+46q\n qHIA==", "X-Gm-Message-State": "AOAM531y3A6L0RjvtCOL/6x3Zp0vFYZGMz2Vdc6kjTWJOtiB4Sgq9t00\n fKMascJT1XozvpncYCmg+HHbwQ==", "X-Google-Smtp-Source": "\n ABdhPJyU0sfqPIuhnTAJkrIBfX6NHdZoGK/pjdmf8z89eluLe7Bsxvm82DmcZ9Rtsf/gdQm/x6lHnw==", "X-Received": "by 2002:a05:6000:11cc:: with SMTP id\n i12mr53416753wrx.224.1594132372926;\n Tue, 07 Jul 2020 07:32:52 -0700 (PDT)", "Date": "Tue, 7 Jul 2020 16:32:51 +0200", "From": "Olivier Matz <olivier.matz@6wind.com>", "To": "Viacheslav Ovsiienko <viacheslavo@mellanox.com>", "Cc": "dev@dpdk.org, matan@mellanox.com, rasland@mellanox.com,\n bernard.iremonger@intel.com, thomas@mellanox.net", "Message-ID": "<20200707143251.GJ5869@platinum>", "References": "<1591771085-24959-1-git-send-email-viacheslavo@mellanox.com>\n <1594127283-19863-1-git-send-email-viacheslavo@mellanox.com>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=us-ascii", "Content-Disposition": "inline", "In-Reply-To": "<1594127283-19863-1-git-send-email-viacheslavo@mellanox.com>", "User-Agent": "Mutt/1.10.1 (2018-07-13)", "Subject": "Re: [dpdk-dev] [PATCH v3 1/2] mbuf: introduce accurate packet Tx\n\tscheduling", "X-BeenThere": "dev@dpdk.org", "X-Mailman-Version": "2.1.15", "Precedence": "list", "List-Id": "DPDK patches and discussions <dev.dpdk.org>", "List-Unsubscribe": "<https://mails.dpdk.org/options/dev>,\n <mailto:dev-request@dpdk.org?subject=unsubscribe>", "List-Archive": "<http://mails.dpdk.org/archives/dev/>", "List-Post": "<mailto:dev@dpdk.org>", "List-Help": "<mailto:dev-request@dpdk.org?subject=help>", "List-Subscribe": "<https://mails.dpdk.org/listinfo/dev>,\n <mailto:dev-request@dpdk.org?subject=subscribe>", "Errors-To": "dev-bounces@dpdk.org", "Sender": "\"dev\" <dev-bounces@dpdk.org>" }, "addressed": null } ]