malloc: fix allocation of almost hugepage size

[dpdk.git] / doc / guides / prog_guide / kernel_nic_interface.rst

diff --git a/doc/guides/prog_guide/kernel_nic_interface.rst b/doc/guides/prog_guide/kernel_nic_interface.rst
index 1ce03ec..5248f96 100644 (file)
--- a/doc/guides/prog_guide/kernel_nic_interface.rst
+++ b/doc/guides/prog_guide/kernel_nic_interface.rst
@@ -56,6 +56,16 @@ can be specified when the module is loaded to control its behavior:
                     off   Interfaces will be created with carrier state set to off.
                     on    Interfaces will be created with carrier state set to on.
                      (charp)
+    parm:           enable_bifurcated: Enable request processing support for
+                    bifurcated drivers, which means releasing rtnl_lock before calling
+                    userspace callback and supporting async requests (default=off):
+                    on    Enable request processing support for bifurcated drivers.
+                     (charp)
+    parm:           min_scheduling_interval: KNI thread min scheduling interval (default=100 microseconds)
+                     (long)
+    parm:           max_scheduling_interval: KNI thread max scheduling interval (default=200 microseconds)
+                     (long)
+
 
 Loading the ``rte_kni`` kernel module without any optional parameters is
 the typical way a DPDK application gets packets into and out of the kernel
@@ -174,6 +184,57 @@ To set the default carrier state to *off*:
 If the ``carrier`` parameter is not specified, the default carrier state
 of KNI interfaces will be set to *off*.
 
+.. _kni_bifurcated_device_support:
+
+Bifurcated Device Support
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+User callbacks are executed while kernel module holds the ``rtnl`` lock, this
+causes a deadlock when callbacks run control commands on another Linux kernel
+network interface.
+
+Bifurcated devices has kernel network driver part and to prevent deadlock for
+them ``enable_bifurcated`` is used.
+
+To enable bifurcated device support:
+
+.. code-block:: console
+
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko enable_bifurcated=on
+
+Enabling bifurcated device support releases ``rtnl`` lock before calling
+callback and locks it back after callback. Also enables asynchronous request to
+support callbacks that requires rtnl lock to work (interface down).
+
+KNI Kthread Scheduling
+~~~~~~~~~~~~~~~~~~~~~~
+
+The ``min_scheduling_interval`` and ``max_scheduling_interval`` parameters
+control the rescheduling interval of the KNI kthreads.
+
+This might be useful if we have use cases in which we require improved
+latency or performance for control plane traffic.
+
+The implementation is backed by Linux High Precision Timers, and uses ``usleep_range``.
+Hence, it will have the same granularity constraints as this Linux subsystem.
+
+For Linux High Precision Timers, you can check the following resource: `Kernel Timers <http://www.kernel.org/doc/Documentation/timers/timers-howto.txt>`_
+
+To set the ``min_scheduling_interval`` to a value of 100 microseconds:
+
+.. code-block:: console
+
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko min_scheduling_interval=100
+
+To set the ``max_scheduling_interval`` to a value of 200 microseconds:
+
+.. code-block:: console
+
+    # insmod <build_dir>/kernel/linux/kni/rte_kni.ko max_scheduling_interval=200
+
+If the ``min_scheduling_interval`` and ``max_scheduling_interval`` parameters are
+not specified, the default interval limits will be set to *100* and *200* respectively.
+
 KNI Creation and Deletion
 -------------------------