From: Olivier Matz <olivier.matz@6wind.com> To: Ferruh Yigit <ferruh.yigit@intel.com> Cc: dev@dpdk.org, Keith Wiles <keith.wiles@intel.com>, Stephen Hemminger <stephen@networkplumber.org>, Thomas Monjalon <thomas@monjalon.net> Subject: Re: [dpdk-dev] [PATCH] doc: note KNI alternatives and deprecation plan Date: Fri, 30 Jul 2021 14:48:13 +0200 Message-ID: <YQP1DSH2qfwQIYzr@platinum> (raw) In-Reply-To: <20210623173142.3803801-1-ferruh.yigit@intel.com> Hi Ferruh, Few minor comments below. On Wed, Jun 23, 2021 at 06:31:42PM +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 <ferruh.yigit@intel.com> > --- > 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 <https://git.dpdk.org/dpdk-kmods/>`_ removed -> moved? Or "removed from main and moved to" > + repository by the `DPDK technical board decision <https://mails.dpdk.org/archives/dev/2021-January/197077.html>`_. > + Also there is a `long term plan <https://mails.dpdk.org/archives/dev/2021-May/209026.html>`_ 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 > + <https://www.kernel.org/doc/Documentation/networking/tuntap.txt>`_ > + > +#. :ref:`virtio_user_as_exceptional_path` Shouldn't virtio_user be the first item? > + > +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 OSV -> OVS > + 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`. > > -- > 2.31.1 >
next prev parent reply other threads:[~2021-07-30 12:48 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-23 17:31 Ferruh Yigit 2021-06-23 18:33 ` Stephen Hemminger 2021-06-24 8:19 ` Ferruh Yigit 2021-07-30 12:48 ` Olivier Matz [this message] 2021-11-23 10:21 ` Ferruh Yigit 2021-08-20 12:58 ` David Marchand 2021-11-23 10:42 ` Ferruh Yigit 2021-11-23 12:08 ` [PATCH v2 1/2] doc: note KNI alternatives Ferruh Yigit 2021-11-23 12:08 ` [PATCH v2 2/2] doc: announce KNI deprecation Ferruh Yigit 2021-11-24 14:00 ` Thomas Monjalon 2021-11-24 13:58 ` [PATCH v2 1/2] doc: note KNI alternatives Thomas Monjalon 2021-11-24 14:19 ` Ferruh Yigit 2021-11-24 17:16 ` [PATCH v3 " Ferruh Yigit 2021-11-24 17:16 ` [PATCH v3 2/2] doc: announce KNI deprecation Ferruh Yigit 2021-12-01 16:31 ` [PATCH v3 1/2] doc: note KNI alternatives Morten Brørup
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