Dataplane

Dataplane and DPDK configuration.

Field	Type	Description	Example
rx_mode	string	Interface RX mode: polling, interrupt, or adaptive	polling
main-core	int	Core for VPP's main thread. Auto-resolved when unset	0
workers	string	Core set for VPP workers. Auto-resolved when unset	1-5
cp-cores	string	Core set for the Go control plane. Auto-resolved when unset	6-7
poll-sleep-usec	int	Microseconds an idle worker sleeps between dispatch loops. Default 100 (low idle CPU); 0 polls continuously for lowest latency	0
dpdk	DPDK	DPDK-specific configuration
statseg	StatsSegment	Stats segment configuration

CPU Cores

Each host resolves core placement locally at startup from the cores actually available to it (container cpusets are respected), so the same config works across hosts with different core counts. Unset fields follow the auto layout:

Cores	VPP main	VPP workers	Control plane
1	0	-	shared (0)
2	0	1	shared (0)
3	0	1	2
4	0	1-2	3
5-7	0	1-(N-2)	N-1
8+	0	1-(N-3)	(N-2)-(N-1)

Explicit sets override the auto layout per field and use the same syntax everywhere: ranges and commas, for example 2-3,34-35. The control plane sizes GOMAXPROCS to its resolved set and is pinned to it, so giving it more cores is a config change, not a build change. Resolution is topology-blind: on a multi-socket host, expressing NUMA placement (workers beside their NICs, control-plane cores on a chosen socket) is done with explicit sets.

dataplane:
  main-core: 0
  workers: 1-5
  cp-cores: 6-7

RX Mode

Controls how VPP polls AF_PACKET host interfaces for incoming packets.

• interrupt (default): Workers sleep until the kernel signals a packet arrival. Near-zero CPU when idle.
• polling: Each worker thread busy-polls its assigned interfaces, pinning its core at 100% CPU even when idle. This is by design in VPP to maximise time spent packet processing and minimise latency.
• adaptive: VPP dynamically switches between polling and interrupt based on traffic load.

LCP tap interfaces are always set to interrupt mode regardless of this setting. These interfaces exist to pass control plane packets (BGP, OSPF, ARP, ND, etc.) into the kernel for FRR and do not benefit from polling.

This setting does not affect DPDK interfaces, which manage their own RX mode independently.

dataplane:
  rx_mode: polling

Worker Poll Sleep

poll-sleep-usec caps how long an idle worker sleeps between dispatch loops, in microseconds. It trades idle CPU against latency.

• 100 (default): idle workers sleep up to 100µs between polls, keeping CPU low when there is no traffic. Best for dev, test, and shared hosts.
• 0: workers never sleep when idle and poll continuously, giving the lowest latency at the cost of pinning each worker core at 100% CPU.

Set poll-sleep-usec: 0 on production deployments. Under load workers are always busy, so the sleep only affects idle workers, but with several workers a low-rate flow (for example ICMP) landing on a worker that is momentarily idle can otherwise wait up to the sleep interval before that worker wakes to handle it. 0 removes that tail. DPDK workers are unaffected under load; this only changes idle-worker behaviour.

dataplane:
  poll-sleep-usec: 0

Stats Segment

Field	Type	Description	Example
size	string	Stats segment size	64m
page-size	string	Page size	2m
per-node-counters	bool	Enable per-node counters	true

DPDK Configuration

Field	Type	Description	Example
uio_driver	string	UIO driver: vfio-pci, uio_pci_generic	vfio-pci
devices	DPDKDevice	List of DPDK devices
dev_defaults	DPDKDeviceOptions	Default device options applied to all devices
socket_mem	string	Hugepage memory per socket	1024,1024
no_multi_seg	bool	Disable multi-segment mbufs	false
no_tx_checksum_offload	bool	Disable TX checksum offload	false
enable_tcp_udp_checksum	bool	Enable TCP/UDP checksum	false
max_simd_bitwidth	int	Max SIMD bitwidth	512

DPDK Devices

Field	Type	Description	Example
pci	string	PCI address	0000:05:00.0
name	string	Interface name	eth1
options	DPDKDeviceOptions	Per-device options

DPDK Device Options

Applies to both per-device options and global dev_defaults.

Field	Type	Description	Example
num_rx_queues	int	Number of RX queues	2
num_tx_queues	int	Number of TX queues	2
num_rx_desc	int	RX descriptor ring size	1024
num_tx_desc	int	TX descriptor ring size	1024
tso	bool	Enable TCP segmentation offload	false
devargs	string	Additional device arguments
rss_queues	string	RSS queue configuration
no_rx_interrupt	bool	Disable RX interrupts	false

Example

dataplane:
  statseg:
    size: 64m
    per-node-counters: true
  dpdk:
    dev_defaults:
      num_rx_queues: 2
      num_tx_queues: 2
    devices:
      - pci: "0000:05:00.0"
        name: eth1
      - pci: "0000:06:00.0"
        name: eth2
        options:
          num_rx_queues: 4
    socket_mem: "1024,1024"