| Message ID | 20210623173142.3803801-1-ferruh.yigit@intel.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Delegated to: | Thomas Monjalon |
| Headers | show |
| Series | doc: note KNI alternatives and deprecation plan | expand |
| Context | Check | Description |
|---|---|---|
| ci/intel-Testing | success | Testing PASS |
| ci/github-robot | success | github build: passed |
| ci/Intel-compilation | success | Compilation OK |
| ci/checkpatch | success | coding style OK |
On Wed, 23 Jun 2021 18:31:42 +0100 Ferruh Yigit <ferruh.yigit@intel.com> 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/>`_ > + 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` > + > +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.
On 6/23/2021 7:33 PM, Stephen Hemminger wrote: > On Wed, 23 Jun 2021 18:31:42 +0100 > Ferruh Yigit <ferruh.yigit@intel.com> 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/>`_ >> + 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` >> + >> +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.
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 >
On Wed, Jun 23, 2021 at 7:32 PM Ferruh Yigit <ferruh.yigit@intel.com> 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. Some suggestions on wording below, feel free to ignore if this sounds like French ;-). > > 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/>`_ The* KNI kernel module will be moved* (Olivier comment) to ... > + repository by the `DPDK technical board decision <https://mails.dpdk.org/archives/dev/2021-January/197077.html>`_. repository following* the `...`_. I'd move this first part in doc/guides/rel_notes/deprecation.rst and/or release notes. Then, reword this as: > + Also there is a `long term plan <https://mails.dpdk.org/archives/dev/2021-May/209026.html>`_ to deprecate the KNI. The `long term plan...`_ is* to deprecate KNI, see <XXX link to deprecation notice/release notes>. > + > + :ref:`virtio_user_as_exceptional_path` alternative is preferred way for is one/a* preferred way > + interfacing with Linux network stack as it is being in-kernel solution and interfacing with the* Linux network stack as it is a* in-kernel and > + similar performance expectations. 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 allows an interface with the kernel network stack and allows management of KNI provides* an interface ... > +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 The* main use case of KNI is to* ... > +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` > + +1 to Olivier comment, for making virtio-user first. > +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: Not sure why we need an extra DPDK, KNI alone is enough. > + > +* 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 as in OS vendors, right? ok for me. > + 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. of net devices control commands* > > The components of an application using the DPDK Kernel NIC Interface are shown in :numref:`figure_kernel_nic_intf`. > > -- > 2.31.1 >
On 7/30/2021 1:48 PM, Olivier Matz wrote: > 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? > ack > 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? > ack >> + >> +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 > I mean 'Operating System Vendor', I will use long version to prevent confusion. >> + 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 >>
On 8/20/2021 1:58 PM, David Marchand wrote: > On Wed, Jun 23, 2021 at 7:32 PM Ferruh Yigit <ferruh.yigit@intel.com> 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. > > Some suggestions on wording below, feel free to ignore if this sounds > like French ;-). > > >> >> 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/>`_ > The* KNI kernel module will be moved* (Olivier comment) to ... > >> + repository by the `DPDK technical board decision <https://mails.dpdk.org/archives/dev/2021-January/197077.html>`_. > repository following* the `...`_. > > I'd move this first part in doc/guides/rel_notes/deprecation.rst Perhaps it is better to clarify the decisions first in the deprecation notice, and document it later referencing it, instead of documenting it first. I will try to separate the decision part from the KNI documentation. > and/or release notes. > Then, reword this as: > >> + Also there is a `long term plan <https://mails.dpdk.org/archives/dev/2021-May/209026.html>`_ to deprecate the KNI. > > The `long term plan...`_ is* to deprecate KNI, see <XXX link to > deprecation notice/release notes>. > > >> + >> + :ref:`virtio_user_as_exceptional_path` alternative is preferred way for > > is one/a* preferred way > ack >> + interfacing with Linux network stack as it is being in-kernel solution and > > interfacing with the* Linux network stack as it is a* in-kernel and > ack >> + similar performance expectations. > > has* similar performance expectations. > ack > >> + >> 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 > > KNI provides* an interface ... > ack >> +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 > > The* main use case of KNI is to* ... > ack >> +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` >> + > > +1 to Olivier comment, for making virtio-user first. > > >> +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: > > Not sure why we need an extra DPDK, KNI alone is enough. > ack > >> + >> +* 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 as in OS vendors, right? ok for me. > > >> + 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. > > of net devices control commands* > ack >> >> The components of an application using the DPDK Kernel NIC Interface are shown in :numref:`figure_kernel_nic_intf`. >> >> -- >> 2.31.1 >> > >
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/>`_ + 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` + +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`.
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(-)