I/O API

Types for mapping I/O devices to NUMA nodes.

DeviceMap

Maps devices to their NUMA nodes.

pub struct DeviceMap { /* internal */ }

Construction

use numaperf::{DeviceMap, Topology};
use std::sync::Arc;

let topo = Arc::new(Topology::discover()?);
let devices = DeviceMap::discover(Arc::clone(&topo))?;

Methods

Method	Description
discover(topo) -> Result<Self, NumaError>	Discover device localities
device_node(&self, name: &str) -> Option<NodeId>	Get node for device
get(&self, name: &str) -> Option<&DeviceLocality>	Get device info
network_devices(&self) -> impl Iterator	Iterate network devices
block_devices(&self) -> impl Iterator	Iterate block devices

Example

let devices = DeviceMap::discover(topo)?;

// Find node for network device
if let Some(node) = devices.device_node("eth0") {
    println!("eth0 is on node {}", node.as_u32());
}

// List all network devices
for dev in devices.network_devices() {
    println!("{}: node {:?}", dev.name(), dev.node_id());
}

---

DeviceLocality

Information about a device's NUMA locality.

pub struct DeviceLocality { /* internal */ }

Methods

Method	Description
name(&self) -> &str	Device name
device_type(&self) -> DeviceType	Device type
node_id(&self) -> Option<NodeId>	NUMA node (if known)
sysfs_path(&self) -> Option<&Path>	Sysfs path

Example

if let Some(dev) = devices.get("eth0") {
    println!("Name: {}", dev.name());
    println!("Type: {:?}", dev.device_type());
    println!("Node: {:?}", dev.node_id());
}

---

DeviceType

Type of I/O device.

pub enum DeviceType {
    /// Network interface
    Network,
    /// Block storage device
    BlockDevice,
}

Usage

match dev.device_type() {
    DeviceType::Network => println!("Network device"),
    DeviceType::BlockDevice => println!("Storage device"),
}

---

Discovery Source

Device locality is read from Linux sysfs:

/sys/class/net/<device>/device/numa_node
/sys/class/block/<device>/device/numa_node

Special Values

• 0, 1, ... - Device on that NUMA node
• -1 - No NUMA affinity (returned as None)

---

Pattern: Device-Local Processing

let devices = DeviceMap::discover(topo)?;
let exec = NumaExecutor::builder(topo).build()?;

// Process on the NIC's node
let nic_node = devices.device_node("eth0")
    .unwrap_or(NodeId::new(0));

exec.submit_to_node(nic_node, || {
    // Process packet on local node
});