DPDK patches and discussions
 help / color / mirror / Atom feed
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


  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20211124171609.3101896-1-ferruh.yigit@intel.com \
    --to=ferruh.yigit@intel.com \
    --cc=david.marchand@redhat.com \
    --cc=dev@dpdk.org \
    --cc=dg@adax.com \
    --cc=eladv6@gmail.com \
    --cc=iryzhov@nfware.com \
    --cc=olivier.matz@6wind.com \
    --cc=stephen@networkplumber.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

DPDK patches and discussions

This inbox may be cloned and mirrored by anyone:

	git clone --mirror http://inbox.dpdk.org/dev/0 dev/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dev dev/ http://inbox.dpdk.org/dev \
		dev@dpdk.org
	public-inbox-index dev

Example config snippet for mirrors.
Newsgroup available over NNTP:
	nntp://inbox.dpdk.org/inbox.dpdk.dev


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git