* Virtio supports software vlan stripping and inserting.
-* Virtio supports using port IO to get PCI resource when uio/igb_uio module is not available.
+* Virtio supports using port IO to get PCI resource when UIO module is not available.
Prerequisites
-------------
insmod rte_kni.ko
- Other basic DPDK preparations like hugepage enabling, uio port binding are not listed here.
+ Other basic DPDK preparations like hugepage enabling,
+ UIO port binding are not listed here.
Please refer to the *DPDK Getting Started Guide* for detailed instructions.
#. Launch the kni user application:
.. code-block:: console
- examples/kni/build/app/kni -l 0-3 -n 4 -- -p 0x1 -P --config="(0,1,3)"
+ <build_dir>/examples/dpdk-kni -l 0-3 -n 4 -- -p 0x1 -P --config="(0,1,3)"
This command generates one network device vEth0 for physical port.
If specify more physical ports, the generated network device will be vEth1, vEth2, and so on.
.. code-block:: console
modprobe uio
- echo 512 > /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages
+ dpdk-hugepages.py --setup 1G
modprobe uio_pci_generic
- python usertools/dpdk-devbind.py -b uio_pci_generic 00:03.0
+ ./usertools/dpdk-devbind.py -b uio_pci_generic 00:03.0
We use testpmd as the forwarding application in this example.
Example of using the vector version of the virtio poll mode driver in
``testpmd``::
- testpmd -l 0-2 -n 4 -- -i --rxq=1 --txq=1 --nb-cores=1
+ dpdk-testpmd -l 0-2 -n 4 -- -i --rxq=1 --txq=1 --nb-cores=1
In-order callbacks only work on simulated virtio user vdev.
.. code-block:: console
- python usertools/dpdk-devbind.py -b vfio-pci 00:03.0
+ ./usertools/dpdk-devbind.py -b vfio-pci 00:03.0
Example
~~~~~~~
.. code-block:: console
- $ l3fwd-power -l 0-1 -- -p 1 -P --config="(0,0,1)" \
+ $ dpdk-l3fwd-power -l 0-1 -- -p 1 -P --config="(0,0,1)" \
--no-numa --parse-ptype
a virtio device needs to work in vDPA mode.
(Default: 0 (disabled))
+#. ``speed``:
+
+ It is used to specify link speed of virtio device. Link speed is a part of
+ link status structure. It could be requested by application using
+ rte_eth_link_get_nowait function.
+ (Default: 0xffffffff (Unknown))
+
+#. ``vectorized``:
+
+ It is used to specify whether virtio device prefers to use vectorized path.
+ Afterwards, dependencies of vectorized path will be checked in path
+ election.
+ (Default: 0 (disabled))
+
Below devargs are supported by the virtio-user vdev:
#. ``path``:
It is used to enable virtio device packed virtqueue feature.
(Default: 0 (disabled))
+
+#. ``speed``:
+
+ It is used to specify link speed of virtio device. Link speed is a part of
+ link status structure. It could be requested by application using
+ rte_eth_link_get_nowait function.
+ (Default: 0xffffffff (Unknown))
+
+#. ``vectorized``:
+
+ It is used to specify whether virtio device prefers to use vectorized path.
+ Afterwards, dependencies of vectorized path will be checked in path
+ election.
+ (Default: 0 (disabled))
+
+Virtio paths Selection and Usage
+--------------------------------
+
+Logically virtio-PMD has 9 paths based on the combination of virtio features
+(Rx mergeable, In-order, Packed virtqueue), below is an introduction of these
+features:
+
+* `Rx mergeable <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
+ virtio-v1.1-cs01.html#x1-2140004>`_: With this feature negotiated, device
+ can receive large packets by combining individual descriptors.
+* `In-order <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
+ virtio-v1.1-cs01.html#x1-690008>`_: Some devices always use descriptors
+ in the same order in which they have been made available, these
+ devices can offer the VIRTIO_F_IN_ORDER feature. With this feature negotiated,
+ driver will use descriptors in order.
+* `Packed virtqueue <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
+ virtio-v1.1-cs01.html#x1-610007>`_: The structure of packed virtqueue is
+ different from split virtqueue, split virtqueue is composed of available ring,
+ used ring and descriptor table, while packed virtqueue is composed of descriptor
+ ring, driver event suppression and device event suppression. The idea behind
+ this is to improve performance by avoiding cache misses and make it easier
+ for hardware to implement.
+
+Virtio paths Selection
+~~~~~~~~~~~~~~~~~~~~~~
+
+If packed virtqueue is not negotiated, below split virtqueue paths will be selected
+according to below configuration:
+
+#. Split virtqueue mergeable path: If Rx mergeable is negotiated, in-order feature is
+ not negotiated, this path will be selected.
+#. Split virtqueue non-mergeable path: If Rx mergeable and in-order feature are not
+ negotiated, also Rx offload(s) are requested, this path will be selected.
+#. Split virtqueue in-order mergeable path: If Rx mergeable and in-order feature are
+ both negotiated, this path will be selected.
+#. Split virtqueue in-order non-mergeable path: If in-order feature is negotiated and
+ Rx mergeable is not negotiated, this path will be selected.
+#. Split virtqueue vectorized Rx path: If Rx mergeable is disabled and no Rx offload
+ requested, this path will be selected.
+
+If packed virtqueue is negotiated, below packed virtqueue paths will be selected
+according to below configuration:
+
+#. Packed virtqueue mergeable path: If Rx mergeable is negotiated, in-order feature
+ is not negotiated, this path will be selected.
+#. Packed virtqueue non-mergeable path: If Rx mergeable and in-order feature are not
+ negotiated, this path will be selected.
+#. Packed virtqueue in-order mergeable path: If in-order and Rx mergeable feature are
+ both negotiated, this path will be selected.
+#. Packed virtqueue in-order non-mergeable path: If in-order feature is negotiated and
+ Rx mergeable is not negotiated, this path will be selected.
+#. Packed virtqueue vectorized Rx path: If building and running environment support
+ (AVX512 || NEON) && in-order feature is negotiated && Rx mergeable
+ is not negotiated && TCP_LRO Rx offloading is disabled && vectorized option enabled,
+ this path will be selected.
+#. Packed virtqueue vectorized Tx path: If building and running environment support
+ (AVX512 || NEON) && in-order feature is negotiated && vectorized option enabled,
+ this path will be selected.
+
+Rx/Tx callbacks of each Virtio path
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Refer to above description, virtio path and corresponding Rx/Tx callbacks will
+be selected automatically. Rx callbacks and Tx callbacks for each virtio path
+are shown in below table:
+
+.. table:: Virtio Paths and Callbacks
+
+ ============================================ ================================= ========================
+ Virtio paths Rx callbacks Tx callbacks
+ ============================================ ================================= ========================
+ Split virtqueue mergeable path virtio_recv_mergeable_pkts virtio_xmit_pkts
+ Split virtqueue non-mergeable path virtio_recv_pkts virtio_xmit_pkts
+ Split virtqueue in-order mergeable path virtio_recv_pkts_inorder virtio_xmit_pkts_inorder
+ Split virtqueue in-order non-mergeable path virtio_recv_pkts_inorder virtio_xmit_pkts_inorder
+ Split virtqueue vectorized Rx path virtio_recv_pkts_vec virtio_xmit_pkts
+ Packed virtqueue mergeable path virtio_recv_mergeable_pkts_packed virtio_xmit_pkts_packed
+ Packed virtqueue non-meregable path virtio_recv_pkts_packed virtio_xmit_pkts_packed
+ Packed virtqueue in-order mergeable path virtio_recv_mergeable_pkts_packed virtio_xmit_pkts_packed
+ Packed virtqueue in-order non-mergeable path virtio_recv_pkts_packed virtio_xmit_pkts_packed
+ Packed virtqueue vectorized Rx path virtio_recv_pkts_packed_vec virtio_xmit_pkts_packed
+ Packed virtqueue vectorized Tx path virtio_recv_pkts_packed virtio_xmit_pkts_packed_vec
+ ============================================ ================================= ========================
+
+Virtio paths Support Status from Release to Release
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Virtio feature implementation:
+
+* In-order feature is supported since DPDK 18.08 by adding new Rx/Tx callbacks
+ ``virtio_recv_pkts_inorder`` and ``virtio_xmit_pkts_inorder``.
+* Packed virtqueue is supported since DPDK 19.02 by adding new Rx/Tx callbacks
+ ``virtio_recv_pkts_packed`` , ``virtio_recv_mergeable_pkts_packed`` and
+ ``virtio_xmit_pkts_packed``.
+
+All virtio paths support status are shown in below table:
+
+.. table:: Virtio Paths and Releases
+
+ ============================================ ============= ============= ============= =======
+ Virtio paths 16.11 ~ 18.05 18.08 ~ 18.11 19.02 ~ 19.11 20.05 ~
+ ============================================ ============= ============= ============= =======
+ Split virtqueue mergeable path Y Y Y Y
+ Split virtqueue non-mergeable path Y Y Y Y
+ Split virtqueue vectorized Rx path Y Y Y Y
+ Split virtqueue simple Tx path Y N N N
+ Split virtqueue in-order mergeable path Y Y Y
+ Split virtqueue in-order non-mergeable path Y Y Y
+ Packed virtqueue mergeable path Y Y
+ Packed virtqueue non-mergeable path Y Y
+ Packed virtqueue in-order mergeable path Y Y
+ Packed virtqueue in-order non-mergeable path Y Y
+ Packed virtqueue vectorized Rx path Y
+ Packed virtqueue vectorized Tx path Y
+ ============================================ ============= ============= ============= =======
+
+QEMU Support Status
+~~~~~~~~~~~~~~~~~~~
+
+* Qemu now supports three paths of split virtqueue: Split virtqueue mergeable path,
+ Split virtqueue non-mergeable path, Split virtqueue vectorized Rx path.
+* Since qemu 4.2.0, Packed virtqueue mergeable path and Packed virtqueue non-mergeable
+ path can be supported.
+
+How to Debug
+~~~~~~~~~~~~
+
+If you meet performance drop or some other issues after upgrading the driver
+or configuration, below steps can help you identify which path you selected and
+root cause faster.
+
+#. Run vhost/virtio test case;
+#. Run "perf top" and check virtio Rx/Tx callback names;
+#. Identify which virtio path is selected refer to above table.
git.droids-corp.org / dpdk.git / blobdiff