From: Ferruh Yigit <ferruh.yigit@intel.com> Cc: Ferruh Yigit <ferruh.yigit@intel.com>, dev@dpdk.org, Olivier Matz Olivier Matz <olivier.matz@6wind.com>, David Marchand David Marchand <david.marchand@redhat.com>, Stephen Hemminger Stephen Hemminger <stephen@networkplumber.org>, Elad Nachman <eladv6@gmail.com>, Igor Ryzhov <iryzhov@nfware.com>, Dan Gora <dg@adax.com> Subject: [PATCH v3 1/2] doc: note KNI alternatives Date: Wed, 24 Nov 2021 17:16:08 +0000 Message-ID: <20211124171609.3101896-1-ferruh.yigit@intel.com> (raw) In-Reply-To: <20210623173142.3803801-1-ferruh.yigit@intel.com> Add more information on alternatives of KNI and the cons of KNI against these alternatives. Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com> --- Cc: Olivier Matz Olivier Matz <olivier.matz@6wind.com> Cc: David Marchand David Marchand <david.marchand@redhat.com> Cc: Stephen Hemminger Stephen Hemminger <stephen@networkplumber.org> Cc: Elad Nachman <eladv6@gmail.com> Cc: Igor Ryzhov <iryzhov@nfware.com> Cc: Dan Gora <dg@adax.com> v3: * reference tap document directly instead of adding label to it. --- .../prog_guide/kernel_nic_interface.rst | 34 +++++++++++++++++-- 1 file changed, 31 insertions(+), 3 deletions(-) diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst index 1ce03ec1a374..f5a8b7c0782c 100644 --- a/doc/guides/prog_guide/kernel_nic_interface.rst +++ b/doc/guides/prog_guide/kernel_nic_interface.rst @@ -6,16 +6,44 @@ Kernel NIC Interface ==================== +.. Note:: + + :ref:`virtio_user_as_exceptional_path` alternative is the preferred way for + interfacing with the Linux network stack as it is an in-kernel solution and + has 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 provides an interface with the kernel network stack and allows management of +DPDK ports using standard Linux net tools such as ``ethtool``, ``ifconfig`` and +``tcpdump``. + +The main use case of KNI is to 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:`virtio_user_as_exceptional_path` + +#. :doc:`../nics/tap` as wrapper to `Linux tun/tap + <https://www.kernel.org/doc/Documentation/networking/tuntap.txt>`_ + +The benefits of using the 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 KNI are: + +* It is out-of-tree Linux kernel module and it can't be distributed as binary as + part of operating system vendor 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 net devices 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:[~2021-11-24 17:21 UTC|newest] Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-23 17:31 [dpdk-dev] [PATCH] doc: note KNI alternatives and deprecation plan Ferruh Yigit 2021-06-23 18:33 ` Stephen Hemminger 2021-06-24 8:19 ` Ferruh Yigit 2021-07-30 12:48 ` Olivier Matz 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 ` Ferruh Yigit [this message] 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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