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.yi...@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 >
