+Loopback Mode
+~~~~~~~~~~~~~
+
+For testing, the ``rte_kni`` kernel module can be loaded in loopback mode
+by specifying the ``lo_mode`` parameter:
+
+.. code-block:: console
+
+ # insmod kmod/rte_kni.ko lo_mode=lo_mode_fifo
+
+The ``lo_mode_fifo`` loopback option will loop back ring enqueue/dequeue
+operations in kernel space.
+
+.. code-block:: console
+
+ # insmod kmod/rte_kni.ko lo_mode=lo_mode_fifo_skb
+
+The ``lo_mode_fifo_skb`` loopback option will loop back ring enqueue/dequeue
+operations and sk buffer copies in kernel space.
+
+If the ``lo_mode`` parameter is not specified, loopback mode is disabled.
+
+.. _kni_kernel_thread_mode:
+
+Kernel Thread Mode
+~~~~~~~~~~~~~~~~~~
+
+To provide flexibility of performance, the ``rte_kni`` KNI kernel module
+can be loaded with the ``kthread_mode`` parameter. The ``rte_kni`` kernel
+module supports two options: "single kernel thread" mode and "multiple
+kernel thread" mode.
+
+Single kernel thread mode is enabled as follows:
+
+.. code-block:: console
+
+ # insmod kmod/rte_kni.ko kthread_mode=single
+
+This mode will create only one kernel thread for all KNI interfaces to
+receive data on the kernel side. By default, this kernel thread is not
+bound to any particular core, but the user can set the core affinity for
+this kernel thread by setting the ``core_id`` and ``force_bind`` parameters
+in ``struct rte_kni_conf`` when the first KNI interface is created:
+
+For optimum performance, the kernel thread should be bound to a core in
+on the same socket as the DPDK lcores used in the application.
+
+The KNI kernel module can also be configured to start a separate kernel
+thread for each KNI interface created by the DPDK application. Multiple
+kernel thread mode is enabled as follows:
+
+.. code-block:: console
+
+ # insmod kmod/rte_kni.ko kthread_mode=multiple
+
+This mode will create a separate kernel thread for each KNI interface to
+receive data on the kernel side. The core affinity of each ``kni_thread``
+kernel thread can be specified by setting the ``core_id`` and ``force_bind``
+parameters in ``struct rte_kni_conf`` when each KNI interface is created.
+
+Multiple kernel thread mode can provide scalable higher performance if
+sufficient unused cores are available on the host system.
+
+If the ``kthread_mode`` parameter is not specified, the "single kernel
+thread" mode is used.
+
+.. _kni_default_carrier_state:
+
+Default Carrier State
+~~~~~~~~~~~~~~~~~~~~~
+
+The default carrier state of KNI interfaces created by the ``rte_kni``
+kernel module is controlled via the ``carrier`` option when the module
+is loaded.
+
+If ``carrier=off`` is specified, the kernel module will leave the carrier
+state of the interface *down* when the interface is management enabled.
+The DPDK application can set the carrier state of the KNI interface using the
+``rte_kni_update_link()`` function. This is useful for DPDK applications
+which require that the carrier state of the KNI interface reflect the
+actual link state of the corresponding physical NIC port.
+
+If ``carrier=on`` is specified, the kernel module will automatically set
+the carrier state of the interface to *up* when the interface is management
+enabled. This is useful for DPDK applications which use the KNI interface as
+a purely virtual interface that does not correspond to any physical hardware
+and do not wish to explicitly set the carrier state of the interface with
+``rte_kni_update_link()``. It is also useful for testing in loopback mode
+where the NIC port may not be physically connected to anything.
+
+To set the default carrier state to *on*:
+
+.. code-block:: console
+
+ # insmod kmod/rte_kni.ko carrier=on
+
+To set the default carrier state to *off*:
+
+.. code-block:: console
+
+ # insmod kmod/rte_kni.ko carrier=off
+
+If the ``carrier`` parameter is not specified, the default carrier state
+of KNI interfaces will be set to *off*.
Code Review / deb_dpdk.git / blobdiff