From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id D1218A0C41; Thu, 24 Jun 2021 10:19:35 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 4B42140141; Thu, 24 Jun 2021 10:19:35 +0200 (CEST) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by mails.dpdk.org (Postfix) with ESMTP id F1DDA4003C for ; Thu, 24 Jun 2021 10:19:33 +0200 (CEST) IronPort-SDR: LYJXOiY8GpYNHFyBuFxfb91icO0R9Ja3UV++NIKQH/z8hdSSBaU86RcdaxBiHimb6hHu4+0imi 1MWgbrxUQC4A== X-IronPort-AV: E=McAfee;i="6200,9189,10024"; a="204418337" X-IronPort-AV: E=Sophos;i="5.83,296,1616482800"; d="scan'208";a="204418337" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2021 01:19:31 -0700 IronPort-SDR: CZR7Jk2aGUlE2Wlp5mE2jGr+UptLghdGHpATzMoDI+5jS24I9o09bB/Vdvfut2l5JXcbd1EtFZ e/BqzPn2XCcg== X-IronPort-AV: E=Sophos;i="5.83,296,1616482800"; d="scan'208";a="406959882" Received: from fyigit-mobl1.ger.corp.intel.com (HELO [10.213.239.46]) ([10.213.239.46]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2021 01:19:30 -0700 To: Stephen Hemminger Cc: dev@dpdk.org, Keith Wiles , Thomas Monjalon References: <20210623173142.3803801-1-ferruh.yigit@intel.com> <20210623113325.7687788f@hermes.local> From: Ferruh Yigit X-User: ferruhy Message-ID: Date: Thu, 24 Jun 2021 09:19:26 +0100 MIME-Version: 1.0 In-Reply-To: <20210623113325.7687788f@hermes.local> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH] doc: note KNI alternatives and deprecation plan X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 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 6/23/2021 7:33 PM, Stephen Hemminger wrote: > On Wed, 23 Jun 2021 18:31:42 +0100 > Ferruh Yigit wrote: > >> Add a note that KNI kernel module will be moved to dpdk-kmods git repo >> and there is a long term plan to deprecate it. >> >> Also add some more details on the alternatives to KNI and cons of the >> KNI against these alternatives. >> >> Signed-off-by: Ferruh Yigit >> --- >> doc/guides/nics/tap.rst | 2 + >> .../prog_guide/kernel_nic_interface.rst | 38 +++++++++++++++++-- >> 2 files changed, 37 insertions(+), 3 deletions(-) >> >> diff --git a/doc/guides/nics/tap.rst b/doc/guides/nics/tap.rst >> index 3ce696b605d1..07315fe32422 100644 >> --- a/doc/guides/nics/tap.rst >> +++ b/doc/guides/nics/tap.rst >> @@ -1,6 +1,8 @@ >> .. SPDX-License-Identifier: BSD-3-Clause >> Copyright(c) 2016 Intel Corporation. >> >> +.. _TunTap_PMD: >> + >> Tun|Tap Poll Mode Driver >> ======================== >> >> diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst >> index 1ce03ec1a374..29f8c92fd9d6 100644 >> --- a/doc/guides/prog_guide/kernel_nic_interface.rst >> +++ b/doc/guides/prog_guide/kernel_nic_interface.rst >> @@ -6,16 +6,48 @@ >> Kernel NIC Interface >> ==================== >> >> +.. Note:: >> + >> + KNI kernel module will be removed from main git repository to `dpdk-kmods `_ >> + repository by the `DPDK technical board decision `_. >> + Also there is a `long term plan `_ to deprecate the KNI. >> + >> + :ref:`virtio_user_as_exceptional_path` alternative is preferred way for >> + interfacing with Linux network stack as it is being in-kernel solution and >> + similar performance expectations. >> + >> The DPDK Kernel NIC Interface (KNI) allows userspace applications access to the Linux* control plane. >> >> -The benefits of using the DPDK KNI are: >> +KNI allows an interface with the kernel network stack and allows management of >> +DPDK ports using standard Linux net tools such as ``ethtool``, ``ifconfig`` and >> +``tcpdump``. >> + >> +Main use case of KNI is get/receive exception packets from/to Linux network >> +stack while main datapath IO is done bypassing the networking stack. >> + >> +There are other alternatives to KNI, all are available in the upstream Linux: >> + >> +#. :ref:`TunTap_PMD` as wrapper to `Linux tun/tap >> + `_ >> + >> +#. :ref:`virtio_user_as_exceptional_path` >> + >> +The benefits of using the DPDK KNI against alternatives are: >> >> * Faster than existing Linux TUN/TAP interfaces >> (by eliminating system calls and copy_to_user()/copy_from_user() operations. >> >> -* Allows management of DPDK ports using standard Linux net tools such as ethtool, ifconfig and tcpdump. >> +The cons of the DPDK KNI are: >> + >> +* It is out-of-tree Linux kernel module and it can't be distributed as binary as >> + part of OSV DPDK packages. This makes it harder to consume, although it is >> + always possible to compile it from the source code. >> + >> +* As it shares memory between userspace and kernelspace, and kernel part >> + directly uses input provided by userspace, it is not safe. This makes hard to >> + upstream the module. >> >> -* Allows an interface with the kernel network stack. >> +* Only a subset of control commands are supported by KNI. >> >> The components of an application using the DPDK Kernel NIC Interface are shown in :numref:`figure_kernel_nic_intf`. >> > > You should also link to virtio user as exception path. In my testing virtio is as fast as KNI and uses less CPU. > Patch mentions from virtio-user alternative, and in the notes it even documents it as preferred way.