net/memif: optimize with one-way barrier

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

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 92dcdb5..fc3ee43 100644 (file)
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -63,7 +63,7 @@ The following is an overview of some key Vhost API functions:
       512).
 
     * zero copy is really good for VM2VM case. For iperf between two VMs, the
       512).
 
     * zero copy is really good for VM2VM case. For iperf between two VMs, the

-      boost could be above 70% (when TSO is enableld).
+      boost could be above 70% (when TSO is enabled).

 
     * For zero copy in VM2NIC case, guest Tx used vring may be starved if the
       PMD driver consume the mbuf but not release them timely.
 
     * For zero copy in VM2NIC case, guest Tx used vring may be starved if the
       PMD driver consume the mbuf but not release them timely.


@@ -92,6 +92,9 @@ The following is an overview of some key Vhost API functions:
       to use vfio-pci driver, please insert vfio-pci kernel module in noiommu
       mode.
 
       to use vfio-pci driver, please insert vfio-pci kernel module in noiommu
       mode.
 

+    * The consumer of zero copy mbufs should consume these mbufs as soon as
+      possible, otherwise it may block the operations in vhost.
+

   - ``RTE_VHOST_USER_IOMMU_SUPPORT``
 
     IOMMU support will be enabled when this flag is set. It is disabled by
   - ``RTE_VHOST_USER_IOMMU_SUPPORT``
 
     IOMMU support will be enabled when this flag is set. It is disabled by


@@ -106,6 +109,14 @@ The following is an overview of some key Vhost API functions:
     Enabling this flag with these Qemu version results in Qemu being blocked
     when multiple queue pairs are declared.
 
     Enabling this flag with these Qemu version results in Qemu being blocked
     when multiple queue pairs are declared.
 

+  - ``RTE_VHOST_USER_POSTCOPY_SUPPORT``
+
+    Postcopy live-migration support will be enabled when this flag is set.
+    It is disabled by default.
+
+    Enabling this flag should only be done when the calling application does
+    not pre-fault the guest shared memory, otherwise migration would fail.
+

 * ``rte_vhost_driver_set_features(path, features)``
 
   This function sets the feature bits the vhost-user driver supports. The
 * ``rte_vhost_driver_set_features(path, features)``
 
   This function sets the feature bits the vhost-user driver supports. The


@@ -274,3 +285,62 @@ Vhost supported vSwitch reference
 
 For more vhost details and how to support vhost in vSwitch, please refer to
 the vhost example in the DPDK Sample Applications Guide.
 
 For more vhost details and how to support vhost in vSwitch, please refer to
 the vhost example in the DPDK Sample Applications Guide.

+
+Vhost data path acceleration (vDPA)
+-----------------------------------
+
+vDPA supports selective datapath in vhost-user lib by enabling virtio ring
+compatible devices to serve virtio driver directly for datapath acceleration.
+
+``rte_vhost_driver_attach_vdpa_device`` is used to configure the vhost device
+with accelerated backend.
+
+Also vhost device capabilities are made configurable to adopt various devices.
+Such capabilities include supported features, protocol features, queue number.
+
+Finally, a set of device ops is defined for device specific operations:
+
+* ``get_queue_num``
+
+  Called to get supported queue number of the device.
+
+* ``get_features``
+
+  Called to get supported features of the device.
+
+* ``get_protocol_features``
+
+  Called to get supported protocol features of the device.
+
+* ``dev_conf``
+
+  Called to configure the actual device when the virtio device becomes ready.
+
+* ``dev_close``
+
+  Called to close the actual device when the virtio device is stopped.
+
+* ``set_vring_state``
+
+  Called to change the state of the vring in the actual device when vring state
+  changes.
+
+* ``set_features``
+
+  Called to set the negotiated features to device.
+
+* ``migration_done``
+
+  Called to allow the device to response to RARP sending.
+
+* ``get_vfio_group_fd``
+
+   Called to get the VFIO group fd of the device.
+
+* ``get_vfio_device_fd``
+
+  Called to get the VFIO device fd of the device.
+
+* ``get_notify_area``
+
+  Called to get the notify area info of the queue.