In the VM, the kernel enic driver may be automatically bound to the VF during
boot. Unbinding it currently hangs due to a known issue with the driver. To
-work around the issue, blacklist the enic module as follows.
+work around the issue, block the enic module as follows.
Please see :ref:`Limitations <enic_limitations>` for limitations in
the use of SR-IOV.
enic_use_vector_rx_handler use the non-scatter avx2 Rx handler
+64B Completion Queue Entry
+--------------------------
+
+Recent VIC adapters support 64B completion queue entries, as well as
+16B entries that are available on all adapter models. ENIC PMD enables
+and uses 64B entries by default, if available. 64B entries generally
+lower CPU cycles per Rx packet, as they avoid partial DMA writes and
+reduce cache contention between DMA and polling CPU. The effect is
+most pronounced when multiple Rx queues are used on Intel platforms
+with Data Direct I/O Technology (DDIO).
+
+If 64B entries are not available, PMD uses 16B entries. The user may
+explicitly disable 64B entries and use 16B entries by setting
+``devarg`` parameter ``cq64=0``. For example::
+
+ -a 12:00.0,cq64=0
+
+To verify the selected entry size, enable debug logging
+(``--log-level=enic,debug``) and check the following messages.
+
+.. code-block:: console
+
+ PMD: rte_enic_pmd: Supported CQ entry sizes: 16 32
+ PMD: rte_enic_pmd: Using 16B CQ entry size
+
.. _enic_limitations:
Limitations
- VF devices are not usable directly from the host. They can only be used
as assigned devices on VM instances.
- Currently, unbind of the ENIC kernel mode driver 'enic.ko' on the VM
- instance may hang. As a workaround, enic.ko should be blacklisted or removed
+ instance may hang. As a workaround, enic.ko should be blocked or removed
from the boot process.
- pci_generic cannot be used as the uio module in the VM. igb_uio or
vfio in non-IOMMU mode can be used.