ENIC PMD is the DPDK poll-mode driver for the Cisco System Inc. VIC Ethernet NICs. These adapters are also referred to as vNICs below. If you are running or would like to run DPDK software applications on Cisco UCS servers using Cisco VIC adapters the following documentation is relevant.
ENIC PMD support is integrated into the DPDK suite. dpdk-<version>.tar.gz should be downloaded from http://dpdk.org
DPDK Configuration Parameters
The following configuration options are available for the ENIC PMD:
vNIC Configuration Parameters
Number of Queues
The maximum number of receive queues (RQs), work queues (WQs) and completion queues (CQs) are configurable on a per vNIC basis through the Cisco UCS Manager (CIMC or UCSM).
These values should be configured as follows:
For example: If the application requires 3 Rx queues, and 3 Tx queues, the vNIC should be configured to have at least 3 WQs, 6 RQs (3 pairs), and 6 CQs (3 for use by WQs + 3 for use by the 3 pairs of RQs).
Size of Queues
Likewise, the number of receive and transmit descriptors are configurable on a per vNIC bases via the UCS Manager and should be greater than or equal to the nb_rx_desc and nb_tx_desc parameters expected to be used in the calls to rte_eth_rx_queue_setup() and rte_eth_tx_queue_setup() respectively. An application requesting more than the set size will be limited to that size.
Unless there is a lack of resources due to creating many vNICs, it is recommended that the WQ and RQ sizes be set to the maximum. This gives the application the greatest amount of flexibility in its queue configuration.
Note: Since the introduction of rx scatter, for performance reasons, this PMD uses two RQs on the vNIC per receive queue in DPDK. One RQ holds descriptors for the start of a packet the second RQ holds the descriptors for the rest of the fragments of a packet. This means that the nb_rx_desc parameter to rte_eth_rx_queue_setup() can be a greater than 4096. The exact amount will depend on the size of the mbufs being used for receives, and the MTU size.
For example: If the mbuf size is 2048, and the MTU is 9000, then receiving a full size packet will take 5 descriptors, 1 from the start of packet queue, and 4 from the second queue. Assuming that the RQ size was set to the maximum of 4096, then the application can specify up to 1024 + 4096 as the nb_rx_desc parameter to rte_eth_rx_queue_setup().
Interrupts
Only one interrupt per vNIC interface should be configured in the UCS manager regardless of the number receive/transmit queues. The ENIC PMD uses this interrupt to get information about link status and errors in the fast path.
Advanced filtering support was added to 1300 series VIC firmware starting with version 2.0.13 for C-series UCS servers and version 3.1.2 for UCSM managed blade servers. In order to enable advanced filtering the ‘Advanced filter’ radio button should be enabled via CIMC or UCSM followed by a reboot of the server.
With advanced filters, perfect matching of all fields of IPv4, IPv6 headers as well as TCP, UDP and SCTP L4 headers is available through flow director. Masking of these feilds for partial match is also supported.
Without advanced filter support, the flow director is limited to IPv4 perfect filtering of the 5-tuple with no masking of fields supported.
VLAN 0 Priority Tagging
If a vNIC is configured in TRUNK mode by the UCS manager, the adapter will priority tag egress packets according to 802.1Q if they were not already VLAN tagged by software. If the adapter is connected to a properly configured switch, there will be no unexpected behavior.
In test setups where an Ethernet port of a Cisco adapter in TRUNK mode is connected point-to-point to another adapter port or connected though a router instead of a switch, all ingress packets will be VLAN tagged. Programs such as l3fwd which do not account for VLAN tags in packets will misbehave. The solution is to enable VLAN stripping on ingress. The follow code fragment is example of how to accomplish this:
vlan_offload = rte_eth_dev_get_vlan_offload(port);
vlan_offload |= ETH_VLAN_STRIP_OFFLOAD;
rte_eth_dev_set_vlan_offload(port, vlan_offload);
The build instructions for the DPDK suite should be followed. By default the ENIC PMD library will be built into the DPDK library.
For configuring and using UIO and VFIO frameworks, please refer the documentation that comes with DPDK suite.
ENIC PMD supports all recent generations of Cisco VIC adapters including:
Any Linux distribution fulfilling the conditions described in Dependencies section of DPDK documentation.
At this point the system should be ready to run DPDK applications. Once the application runs to completion, the vNIC can be detached from vfio-pci or igb_uio if necessary.
Root privilege is required to bind and unbind vNICs to/from VFIO/UIO. VFIO framework helps an unprivileged user to run the applications. For an unprivileged user to run the applications on DPDK and ENIC PMD, it may be necessary to increase the maximum locked memory of the user. The following command could be used to do this.
sudo sh -c "ulimit -l <value in Kilo Bytes>"
The value depends on the memory configuration of the application, DPDK and PMD. Typically, the limit has to be raised to higher than 2GB. e.g., 2621440
The compilation of any unused drivers can be disabled using the configuration file in config/ directory (e.g., config/common_linuxapp). This would help in bringing down the time taken for building the libraries and the initialization time of the application.
Any questions or bugs should be reported to DPDK community and to the ENIC PMD maintainers: