7. ENIC Poll Mode Driver
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.
7.1. How to obtain ENIC PMD integrated DPDK
ENIC PMD support is integrated into the DPDK suite. dpdk-<version>.tar.gz should be downloaded from http://dpdk.org
7.2. Configuration information
DPDK Configuration Parameters
The following configuration options are available for the ENIC PMD:
- CONFIG_RTE_LIBRTE_ENIC_PMD (default y): Enables or disables inclusion of the ENIC PMD driver in the DPDK compilation.
- CONFIG_RTE_LIBRTE_ENIC_DEBUG (default n): Enables or disables debug logging within the ENIC PMD driver.
vNIC Configuration Parameters
Number of Queues
The maximum number of receive and transmit queues are configurable on a per vNIC basis through the Cisco UCS Manager (CIMC or UCSM). These values should be configured to be greater than or equal to the nb_rx_q and nb_tx_q parameters expected to used in the call to the rte_eth_dev_configure() function.
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.
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 errors in the fast path.
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;
7.4. How to build the suite?
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.
7.5. Supported Cisco VIC adapters
ENIC PMD supports all recent generations of Cisco VIC adapters including:
- Flow director features are not supported on generation 1 Cisco VIC adapters
(M81KR and P81E)
7.6. Supported Operating Systems
Any Linux distribution fulfilling the conditions described in Dependencies section of DPDK documentation.
7.7. Supported features
- Unicast, multicast and broadcast transmission and reception
- Receive queue polling
- Port Hardware Statistics
- Hardware VLAN acceleration
- IP checksum offload
- Receive side VLAN stripping
- Multiple receive and transmit queues
- Flow Director ADD, UPDATE, DELETE, STATS operation support for IPV4 5-TUPLE flows
- Promiscuous mode
- Setting RX VLAN (supported via UCSM/CIMC only)
- VLAN filtering (supported via UCSM/CIMC only)
- Execution of application by unprivileged system users
- IPV4, IPV6 and TCP RSS hashing
- Scattered Rx
- MTU update
7.8. Known bugs and Unsupported features in this release
- Signature or flex byte based flow direction
- Drop feature of flow direction
- VLAN based flow direction
- non-IPV4 flow direction
- Setting of extended VLAN
- UDP RSS hashing
- MTU update only works if Scattered Rx mode is disabled
- Prepare the system as recommended by DPDK suite. This includes environment variables, hugepages configuration, tool-chains and configuration
- Insert vfio-pci kernel module using the command ‘modprobe vfio-pci’ if the user wants to use VFIO framework
- Insert uio kernel module using the command ‘modprobe uio’ if the user wants to use UIO framework
- DPDK suite should be configured based on the user’s decision to use VFIO or UIO framework
- If the vNIC device(s) to be used is bound to the kernel mode Ethernet driver (enic), use ‘ifconfig’ to bring the interface down. The dpdk-devbind.py tool can then be used to unbind the device’s bus id from the enic kernel mode driver.
- Bind the intended vNIC to vfio-pci in case the user wants ENIC PMD to use VFIO framework using dpdk-devbind.py.
- Bind the intended vNIC to igb_uio in case the user wants ENIC PMD to use UIO framework using dpdk-devbind.py.
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.