X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=doc%2Fguides%2Fprog_guide%2Fvhost_lib.rst;h=b892eec67a90130563ef2ea0bb5309161d090029;hb=362f06f9a430d65e96a8bb8e972570bedd3ece5d;hp=07e40e3c5e83546a5396fab9c5396853700a6025;hpb=c3ff0ac70acb1f4a1b22fa24160fdc3be4597724;p=dpdk.git

diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
index 07e40e3c5e..b892eec67a 100644
--- a/doc/guides/prog_guide/vhost_lib.rst
+++ b/doc/guides/prog_guide/vhost_lib.rst
@@ -104,11 +104,6 @@ The following is an overview of some key Vhost API functions:
     from accessing memory the virtio device isn't allowed to, when the feature
     is negotiated and an IOMMU device is declared.
 
-    However, this feature enables vhost-user's reply-ack protocol feature,
-    which implementation is buggy in Qemu v2.7.0-v2.9.0 when doing multiqueue.
-    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.
@@ -152,6 +147,21 @@ The following is an overview of some key Vhost API functions:
 
     It is disabled by default.
 
+  - ``RTE_VHOST_USER_ASYNC_COPY``
+
+    Asynchronous data path will be enabled when this flag is set. Async data
+    path allows applications to register async copy devices (typically
+    hardware DMA channels) to the vhost queues. Vhost leverages the copy
+    device registered to free CPU from memory copy operations. A set of
+    async data path APIs are defined for DPDK applications to make use of
+    the async capability. Only packets enqueued/dequeued by async APIs are
+    processed through the async data path.
+
+    Currently this feature is only implemented on split ring enqueue data
+    path.
+
+    It is disabled by default.
+
 * ``rte_vhost_driver_set_features(path, features)``
 
   This function sets the feature bits the vhost-user driver supports. The
@@ -240,6 +250,59 @@ The following is an overview of some key Vhost API functions:
 
   Enable or disable zero copy feature of the vhost crypto backend.
 
+* ``rte_vhost_async_channel_register(vid, queue_id, features, ops)``
+
+  Register a vhost queue with async copy device channel.
+  Following device ``features`` must be specified together with the
+  registration:
+
+  * ``async_inorder``
+
+    Async copy device can guarantee the ordering of copy completion
+    sequence. Copies are completed in the same order with that at
+    the submission time.
+
+    Currently, only ``async_inorder`` capable device is supported by vhost.
+
+  * ``async_threshold``
+
+    The copy length (in bytes) below which CPU copy will be used even if
+    applications call async vhost APIs to enqueue/dequeue data.
+
+    Typical value is 512~1024 depending on the async device capability.
+
+  Applications must provide following ``ops`` callbacks for vhost lib to
+  work with the async copy devices:
+
+  * ``transfer_data(vid, queue_id, descs, opaque_data, count)``
+
+    vhost invokes this function to submit copy data to the async devices.
+    For non-async_inorder capable devices, ``opaque_data`` could be used
+    for identifying the completed packets.
+
+  * ``check_completed_copies(vid, queue_id, opaque_data, max_packets)``
+
+    vhost invokes this function to get the copy data completed by async
+    devices.
+
+* ``rte_vhost_async_channel_unregister(vid, queue_id)``
+
+  Unregister the async copy device channel from a vhost queue.
+
+* ``rte_vhost_submit_enqueue_burst(vid, queue_id, pkts, count)``
+
+  Submit an enqueue request to transmit ``count`` packets from host to guest
+  by async data path. Enqueue is not guaranteed to finish upon the return of
+  this API call.
+
+  Applications must not free the packets submitted for enqueue until the
+  packets are completed.
+
+* ``rte_vhost_poll_enqueue_completed(vid, queue_id, pkts, count)``
+
+  Poll enqueue completion status from async data path. Completed packets
+  are returned to applications through ``pkts``.
+
 Vhost-user Implementations
 --------------------------
 
@@ -299,16 +362,16 @@ Guest memory requirement
 
 * Memory pre-allocation
 
-  For non-zerocopy, guest memory pre-allocation is not a must. This can help
-  save of memory. If users really want the guest memory to be pre-allocated
-  (e.g., for performance reason), we can add option ``-mem-prealloc`` when
-  starting QEMU. Or, we can lock all memory at vhost side which will force
-  memory to be allocated when mmap at vhost side; option --mlockall in
-  ovs-dpdk is an example in hand.
+  For non-zerocopy non-async data path, guest memory pre-allocation is not a
+  must. This can help save of memory. If users really want the guest memory
+  to be pre-allocated (e.g., for performance reason), we can add option
+  ``-mem-prealloc`` when starting QEMU. Or, we can lock all memory at vhost
+  side which will force memory to be allocated when mmap at vhost side;
+  option --mlockall in ovs-dpdk is an example in hand.
 
-  For zerocopy, we force the VM memory to be pre-allocated at vhost lib when
-  mapping the guest memory; and also we need to lock the memory to prevent
-  pages being swapped out to disk.
+  For async and zerocopy data path, we force the VM memory to be
+  pre-allocated at vhost lib when mapping the guest memory; and also we need
+  to lock the memory to prevent pages being swapped out to disk.
 
 * Memory sharing