Ethernet IRQ RPS CPU SMP Affinity

eth-irq

#!/bin/bash

match=eth0 # Network interface name
num_big_cores=2 # Number of high-performance cores to select

# Retrieve cpu_capacity for each core and sort in descending order
get_cpu_capacities() {
    for cpu in /sys/devices/system/cpu/cpu[0-9]*; do
        capacity_file="$cpu/cpu_capacity"
        if [ -f "$capacity_file" ]; then
            capacity=$(cat "$capacity_file")
            cpu_number=$(basename "$cpu" | grep -o '[0-9]*')
            echo "$cpu_number $capacity"
        fi
    done
}

# Sort and select the highest performance cores
sorted_cores=$(get_cpu_capacities | sort -k2 -nr | head -n "$num_big_cores" | awk '{print $1}')

# Exit if no high-performance cores are found
if [ -z "$sorted_cores" ]; then
    echo "No high-performance cores found. Please check system configuration."
    exit 1
fi

# Generate smp_affinity_list in comma-separated format, and rps_cpus in hex bitmask format
smp_affinity_list=$(echo "$sorted_cores" | tr '\n' ',' | sed 's/,$//')
cpu_bitmask=0
for core in $sorted_cores; do
    cpu_bitmask=$((cpu_bitmask | (1 << core)))
done
hex_bitmask=$(printf '%x' "$cpu_bitmask")

# Iterate through all possible IRQ paths, configure smp_affinity_list and rps_cpus
queue_index=0
while [ -f "/sys/class/net/${match}/queues/rx-${queue_index}/rps_cpus" ]; do
    # Set RPS CPU bitmask for each RX queue
    echo "$hex_bitmask" > "/sys/class/net/${match}/queues/rx-${queue_index}/rps_cpus"
    echo "Set /sys/class/net/${match}/queues/rx-${queue_index}/rps_cpus to $hex_bitmask"

    # Traverse the /proc/irq directory to locate corresponding IRQ files
    for irq_path in /proc/irq/*/${match}-rx-${queue_index} /proc/irq/*/${match}; do
        if [ -e "$irq_path" ]; then
            irq=$(basename "$(dirname "$irq_path")")
            if [ -f /proc/irq/${irq}/smp_affinity_list ]; then
                echo "$smp_affinity_list" > /proc/irq/${irq}/smp_affinity_list
                echo "Set /proc/irq/${irq}/smp_affinity_list to $smp_affinity_list"
            fi
        fi
    done

    queue_index=$((queue_index + 1))
done