From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 48885A00C5; Thu, 4 Jun 2020 12:52:21 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 205CB1D5F4; Thu, 4 Jun 2020 12:52:21 +0200 (CEST) Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by dpdk.org (Postfix) with ESMTP id 3A02F1D5F4 for ; Thu, 4 Jun 2020 12:52:20 +0200 (CEST) IronPort-SDR: lyNRIpdn42QaS033tRrTu2EJUB1A3huc8dRCrFjqdKKpOLXGKquoMdxG0l3o83UQgQ50O3VEqb F69odWQMLXew== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Jun 2020 03:52:18 -0700 IronPort-SDR: W3QhKhc+zft6x1QIjexazOqTgNsrvXII96+2tkN9ts1wK6jO+fQSecC6t6horfnllBxdFuoNVt adfeDSHaePhA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,472,1583222400"; d="scan'208";a="471490359" Received: from fyigit-mobl.ger.corp.intel.com (HELO [10.213.233.208]) ([10.213.233.208]) by fmsmga005.fm.intel.com with ESMTP; 04 Jun 2020 03:52:16 -0700 To: Vivien Didelot , Stephen Hemminger Cc: dev@dpdk.org, patrick.keroulas@radio-canada.ca, thomas@monjalon.net References: <20200523172130.2285380-1-vivien.didelot@gmail.com> <1d7b6c2e-84a9-5e20-1353-4f64de667b03@intel.com> <20200603131139.6f79ecc7@hermes.lan> <20200603162652.GB13716@t480s.localdomain> From: Ferruh Yigit Autocrypt: addr=ferruh.yigit@intel.com; prefer-encrypt=mutual; keydata= mQINBFXZCFABEADCujshBOAaqPZpwShdkzkyGpJ15lmxiSr3jVMqOtQS/sB3FYLT0/d3+bvy qbL9YnlbPyRvZfnP3pXiKwkRoR1RJwEo2BOf6hxdzTmLRtGtwWzI9MwrUPj6n/ldiD58VAGQ +iR1I/z9UBUN/ZMksElA2D7Jgg7vZ78iKwNnd+vLBD6I61kVrZ45Vjo3r+pPOByUBXOUlxp9 GWEKKIrJ4eogqkVNSixN16VYK7xR+5OUkBYUO+sE6etSxCr7BahMPKxH+XPlZZjKrxciaWQb +dElz3Ab4Opl+ZT/bK2huX+W+NJBEBVzjTkhjSTjcyRdxvS1gwWRuXqAml/sh+KQjPV1PPHF YK5LcqLkle+OKTCa82OvUb7cr+ALxATIZXQkgmn+zFT8UzSS3aiBBohg3BtbTIWy51jNlYdy ezUZ4UxKSsFuUTPt+JjHQBvF7WKbmNGS3fCid5Iag4tWOfZoqiCNzxApkVugltxoc6rG2TyX CmI2rP0mQ0GOsGXA3+3c1MCdQFzdIn/5tLBZyKy4F54UFo35eOX8/g7OaE+xrgY/4bZjpxC1 1pd66AAtKb3aNXpHvIfkVV6NYloo52H+FUE5ZDPNCGD0/btFGPWmWRmkPybzColTy7fmPaGz cBcEEqHK4T0aY4UJmE7Ylvg255Kz7s6wGZe6IR3N0cKNv++O7QARAQABtCVGZXJydWggWWln aXQgPGZlcnJ1aC55aWdpdEBpbnRlbC5jb20+iQJsBBMBCgBWAhsDAh4BAheABQsJCAcDBRUK CQgLBRYCAwEABQkKqZZ8FiEE0jZTh0IuwoTjmYHH+TPrQ98TYR8FAl6ha3sXGHZrczovL2tl eXMub3BlbnBncC5vcmcACgkQ+TPrQ98TYR8uLA//QwltuFliUWe60xwmu9sY38c1DXvX67wk UryQ1WijVdIoj4H8cf/s2KtyIBjc89R254KMEfJDao/LrXqJ69KyGKXFhFPlF3VmFLsN4XiT PSfxkx8s6kHVaB3O183p4xAqnnl/ql8nJ5ph9HuwdL8CyO5/7dC/MjZ/mc4NGq5O9zk3YRGO lvdZAp5HW9VKW4iynvy7rl3tKyEqaAE62MbGyfJDH3C/nV/4+mPc8Av5rRH2hV+DBQourwuC ci6noiDP6GCNQqTh1FHYvXaN4GPMHD9DX6LtT8Fc5mL/V9i9kEVikPohlI0WJqhE+vQHFzR2 1q5nznE+pweYsBi3LXIMYpmha9oJh03dJOdKAEhkfBr6n8BWkWQMMiwfdzg20JX0o7a/iF8H 4dshBs+dXdIKzPfJhMjHxLDFNPNH8zRQkB02JceY9ESEah3wAbzTwz+e/9qQ5OyDTQjKkVOo cxC2U7CqeNt0JZi0tmuzIWrfxjAUulVhBmnceqyMOzGpSCQIkvalb6+eXsC9V1DZ4zsHZ2Mx Hi+7pCksdraXUhKdg5bOVCt8XFmx1MX4AoV3GWy6mZ4eMMvJN2hjXcrreQgG25BdCdcxKgqp e9cMbCtF+RZax8U6LkAWueJJ1QXrav1Jk5SnG8/5xANQoBQKGz+yFiWcgEs9Tpxth15o2v59 gXK5Ag0EV9ZMvgEQAKc0Db17xNqtSwEvmfp4tkddwW9XA0tWWKtY4KUdd/jijYqc3fDD54ES YpV8QWj0xK4YM0dLxnDU2IYxjEshSB1TqAatVWz9WtBYvzalsyTqMKP3w34FciuL7orXP4Ai bPtrHuIXWQOBECcVZTTOdZYGAzaYzxiAONzF9eTiwIqe9/oaOjTwTLnOarHt16QApTYQSnxD UQljeNvKYt1lZE/gAUUxNLWsYyTT+22/vU0GDUahsJxs1+f1yEr+OGrFiEAmqrzpF0lCS3f/ 3HVTU6rS9cK3glVUeaTF4+1SK5ZNO35piVQCwphmxa+dwTG/DvvHYCtgOZorTJ+OHfvCnSVj sM4kcXGjJPy3JZmUtyL9UxEbYlrffGPQI3gLXIGD5AN5XdAXFCjjaID/KR1c9RHd7Oaw0Pdc q9UtMLgM1vdX8RlDuMGPrj5sQrRVbgYHfVU/TQCk1C9KhzOwg4Ap2T3tE1umY/DqrXQgsgH7 1PXFucVjOyHMYXXugLT8YQ0gcBPHy9mZqw5mgOI5lCl6d4uCcUT0l/OEtPG/rA1lxz8ctdFB VOQOxCvwRG2QCgcJ/UTn5vlivul+cThi6ERPvjqjblLncQtRg8izj2qgmwQkvfj+h7Ex88bI 8iWtu5+I3K3LmNz/UxHBSWEmUnkg4fJlRr7oItHsZ0ia6wWQ8lQnABEBAAGJAjwEGAEKACYC GwwWIQTSNlOHQi7ChOOZgcf5M+tD3xNhHwUCXqFrngUJCKxSYAAKCRD5M+tD3xNhH3YWD/9b cUiWaHJasX+OpiuZ1Li5GG3m9aw4lR/k2lET0UPRer2Jy1JsL+uqzdkxGvPqzFTBXgx/6Byz EMa2mt6R9BCyR286s3lxVS5Bgr5JGB3EkpPcoJT3A7QOYMV95jBiiJTy78Qdzi5LrIu4tW6H o0MWUjpjdbR01cnj6EagKrDx9kAsqQTfvz4ff5JIFyKSKEHQMaz1YGHyCWhsTwqONhs0G7V2 0taQS1bGiaWND0dIBJ/u0pU998XZhmMzn765H+/MqXsyDXwoHv1rcaX/kcZIcN3sLUVcbdxA WHXOktGTQemQfEpCNuf2jeeJlp8sHmAQmV3dLS1R49h0q7hH4qOPEIvXjQebJGs5W7s2vxbA 5u5nLujmMkkfg1XHsds0u7Zdp2n200VC4GQf8vsUp6CSMgjedHeF9zKv1W4lYXpHp576ZV7T GgsEsvveAE1xvHnpV9d7ZehPuZfYlP4qgo2iutA1c0AXZLn5LPcDBgZ+KQZTzm05RU1gkx7n gL9CdTzVrYFy7Y5R+TrE9HFUnsaXaGsJwOB/emByGPQEKrupz8CZFi9pkqPuAPwjN6Wonokv ChAewHXPUadcJmCTj78Oeg9uXR6yjpxyFjx3vdijQIYgi5TEGpeTQBymLANOYxYWYOjXk+ae dYuOYKR9nbPv+2zK9pwwQ2NXbUBystaGyQ== Message-ID: <1a562b11-b666-e900-c345-ffccb71fdfe2@intel.com> Date: Thu, 4 Jun 2020 11:52:16 +0100 MIME-Version: 1.0 In-Reply-To: <20200603162652.GB13716@t480s.localdomain> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH 1/2] net/pcap: support software Tx nanosecond timestamp X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 6/3/2020 9:26 PM, Vivien Didelot wrote: > On Wed, 3 Jun 2020 13:11:39 -0700, Stephen Hemminger wrote: >> On Wed, 3 Jun 2020 18:50:51 +0100 >> Ferruh Yigit wrote: >> >>> On 5/23/2020 6:21 PM, Vivien Didelot wrote: >>>> When capturing packets into a PCAP file, DPDK currently uses >>>> microseconds for the timestamp. But libpcap supports interpreting >>>> tv_usec as nanoseconds depending on the file timestamp precision. >>>> >>>> To support this, use PCAP_TSTAMP_PRECISION_NANO when creating the >>>> empty PCAP file as specified by PCAP_OPEN_DEAD(3PCAP) and implement >>>> nanosecond timeval addition. This also ensures that the precision >>>> reported by capinfos is nanoseconds (9). >>> >>> Overall good idea and patch looks good. >>> >>> Only concern is change in the libpcap dependency. Do you know which libpcap >>> version supports 'PCAP_TSTAMP_PRECISION_NANO'? >>> If a user of pcap PMD updates to latest DPDK and the environment doesn't have >>> new version of the libpcap, this change will require an environment update and >>> this may or may not be easy to do. That is why not sure if the updates require >>> dependency change should wait for the LTS or not. >>> >>> Another things is the backward compatibility, as far as I understand the pcap >>> file recorded with nanosecond precision can be read and parsed without problem >>> by old application that doesn't know the nanosecond precision, but can you >>> please confirm this? >> >> We should do pcapng instead of doing the pcap with nano timestamp. >> My impression is that libpcap is a dormant project at this point, and the >> finer grain timestamp is a hack that is only in some verisions. >> That was one of the reasons pcapng started. > > Reading tv_usec as nanoseconds has been supported for years in libpcap. > > For instance PCAP_TSTAMP_PRECISION_NANO was introduced in ba89e4a18e8b > ("Make timestamps precision configurable") on May 17, 2013. Thanks for the commit info, it looks like this support exists since libpcap-1.5.0, and even CentOS 7 has libpcap-1.5.3-xx so looks safe to proceed.