#!/bin/sh /etc/rc.common

uci_banirq=irqbalance.irqbalance.banirq
cpu_irq_eth=2

move_eth0_irq() {
    # Move eth0 IRQs to CPU1 (numbered 1-4 when writing)
    # And ban irqbalance from messing with it
    # The USB3 Ethernet IRQs cannot be moved and must stay on CPU0
    irqs_eth0=$(sed -rn "s/^\s*([0-9]+):.*eth0$/\1/p" /proc/interrupts)

    for n in ${irqs_eth0}; do
        echo ${cpu_irq_eth} > /proc/irq/${n}/smp_affinity
        if ! uci get ${uci_banirq} | grep -q ${n}; then
            uci add_list ${uci_banirq}=${n}
        fi
    done
    uci commit irqbalance

    logger -t "irq_eth_pin" "Moved eth0 IRQs ${irqs_eth0} to cpu${cpu_irq_eth}"
    logger -t "irq_eth_pin" "See all interrupts with: cat /proc/interrupts"
}

move_softirqs() {
    # Move softirqs for network traffic to CPU2 and CPU3
    # Maybe not a brilliant idea because the softirqs are probably better off
    # being processed on the CPU that got the original IRQ
    # (and that is exactly the default when the value is 0)
    # NOTE: it appears that the openwrt 20.02-rc1 kernel has a bug that
    # returns "No such file or directory" for /sys/class/net/eth1/queues/xps_cpus
    for ifname in eth0; do # eth1
        for f in $(find /sys/class/net/${ifname}/queues -name xps_cpus -o -name rps_cpus); do
            if [ -f ${f} ]; then
                echo "${f} = $(cat ${f})"
                echo c >${f}
            fi
        done
    done
}

start_service() {
    move_eth0_irq
}