netifd: rewrite packet steering script
The new script uses a different strategy compared to the previous one. Instead of trying to split flows by hash and spread them to all CPUs, use RPS to redirect packets to a single core only. Try to spread NAPI thread and RPS target CPUs across available CPUs and try to ensure that the NAPI thread is on a different CPU than the RPS target. This significantly reduces cycles wasted on the scheduler. Signed-off-by: Felix Fietkau <nbd@nbd.name>
This commit is contained in:
Felix Fietkau
parent
c2f52e42b1
commit
a205a5734e
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@ -21,7 +21,7 @@ include $(INCLUDE_DIR)/cmake.mk
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define Package/netifd
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SECTION:=base
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CATEGORY:=Base system
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DEPENDS:=+libuci +libnl-tiny +libubus +ubus +ubusd +jshn +libubox +libudebug
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DEPENDS:=+libuci +libnl-tiny +libubus +ubus +ubusd +jshn +libubox +libudebug +ucode +ucode-mod-fs
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TITLE:=OpenWrt Network Interface Configuration Daemon
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endef
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@ -14,5 +14,10 @@ service_triggers() {
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}
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reload_service() {
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/usr/libexec/network/packet-steering.sh
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packet_steering="$(uci get "network.@globals[0].packet_steering")"
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if [ -e "/usr/libexec/platform/packet-steering.sh" ]; then
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/usr/libexec/platform/packet-steering.sh "$packet_steering"
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else
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/usr/libexec/network/packet-steering.uc "$packet_steering"
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fi
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}
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@ -1,70 +0,0 @@
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#!/bin/sh
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NPROCS="$(grep -c "^processor.*:" /proc/cpuinfo)"
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[ "$NPROCS" -gt 1 ] || exit
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PROC_MASK="$(( (1 << $NPROCS) - 1 ))"
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find_irq_cpu() {
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local dev="$1"
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local match="$(grep -m 1 "$dev\$" /proc/interrupts)"
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local cpu=0
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[ -n "$match" ] && {
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set -- $match
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shift
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for cur in $(seq 1 $NPROCS); do
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[ "$1" -gt 0 ] && {
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cpu=$(($cur - 1))
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break
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}
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shift
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done
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}
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echo "$cpu"
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}
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set_hex_val() {
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local file="$1"
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local val="$2"
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val="$(printf %x "$val")"
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[ -n "$DEBUG" ] && echo "$file = $val"
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echo "$val" > "$file"
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}
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packet_steering="$(uci get "network.@globals[0].packet_steering")"
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[ "$packet_steering" != 1 ] && exit 0
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exec 512>/var/lock/smp_tune.lock
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flock 512 || exit 1
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[ -e "/usr/libexec/platform/packet-steering.sh" ] && {
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/usr/libexec/platform/packet-steering.sh
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exit 0
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}
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for dev in /sys/class/net/*; do
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[ -d "$dev" ] || continue
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# ignore virtual interfaces
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[ -n "$(ls "${dev}/" | grep '^lower_')" ] && continue
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[ -d "${dev}/device" ] || continue
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device="$(readlink "${dev}/device")"
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device="$(basename "$device")"
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irq_cpu="$(find_irq_cpu "$device")"
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irq_cpu_mask="$((1 << $irq_cpu))"
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for q in ${dev}/queues/tx-*; do
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set_hex_val "$q/xps_cpus" "$PROC_MASK"
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done
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# ignore dsa slave ports for RPS
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subsys="$(readlink "${dev}/device/subsystem")"
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subsys="$(basename "$subsys")"
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[ "$subsys" = "mdio_bus" ] && continue
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for q in ${dev}/queues/rx-*; do
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set_hex_val "$q/rps_cpus" "$PROC_MASK"
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done
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done
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@ -0,0 +1,200 @@
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#!/usr/bin/env ucode
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'use strict';
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import { glob, basename, dirname, readlink, readfile, realpath, writefile, error, open } from "fs";
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let napi_weight = 1.0;
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let cpu_thread_weight = 0.75;
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let rx_weight = 0.75;
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let eth_bias = 2.0;
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let debug = 0, do_nothing = 0;
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let disable;
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let cpus;
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for (let arg in ARGV) {
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switch (arg) {
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case "-d":
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debug++;
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break;
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case "-n":
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do_nothing++;
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break;
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case '0':
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disable = true;
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break;
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}
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}
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function task_name(pid)
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{
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let stat = open(`/proc/${pid}/status`, "r");
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let line = stat.read("line");
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stat.close();
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return trim(split(line, "\t", 2)[1]);
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}
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function set_task_cpu(pid, cpu) {
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if (disable)
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cpu = join(",", map(cpus, (cpu) => cpu.id));
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if (debug || do_nothing)
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warn(`taskset -p -c ${cpu} ${task_name(pid)}\n`);
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if (!do_nothing)
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system(`taskset -p -c ${cpu} ${pid}`);
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}
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function set_netdev_cpu(dev, cpu) {
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let queues = glob(`/sys/class/net/${dev}/queues/rx-*/rps_cpus`);
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let val = sprintf("%x", (1 << int(cpu)));
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if (disable)
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val = 0;
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for (let queue in queues) {
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if (debug || do_nothing)
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warn(`echo ${val} > ${queue}\n`);
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if (!do_nothing)
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writefile(queue, `${val}`);
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}
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}
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function task_device_match(name, device)
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{
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let napi_match = match(name, /napi\/([^-+])-\d+/);
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if (!napi_match)
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napi_match = match(name, /mt76-tx (phy\d+)/);
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if (napi_match &&
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(index(device.phy, napi_match[1]) >= 0 ||
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index(device.netdev, napi_match[1]) >= 0))
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return true;
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if (device.driver == "mtk_soc_eth" && match(name, /napi\/mtk_eth-/))
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return true;
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return false;
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}
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cpus = map(glob("/sys/bus/cpu/devices/*"), (path) => {
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return {
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id: int(match(path, /.*cpu(\d+)/)[1]),
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core: int(trim(readfile(`${path}/topology/core_id`))),
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load: 0.0,
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};
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});
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cpus = slice(cpus, 0, 64);
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if (length(cpus) < 2)
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exit(0);
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function cpu_add_weight(cpu_id, weight)
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{
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let cpu = cpus[cpu_id];
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cpu.load += weight;
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for (let sibling in cpus) {
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if (sibling == cpu || sibling.core != cpu.core)
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continue;
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sibling.load += weight * cpu_thread_weight;
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}
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}
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function get_next_cpu(weight, prev_cpu)
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{
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if (disable)
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return 0;
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let sort_cpus = sort(slice(cpus), (a, b) => a.load - b.load);
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let idx = 0;
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if (prev_cpu != null && sort_cpus[idx].id == prev_cpu)
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idx++;
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let cpu = sort_cpus[idx].id;
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cpu_add_weight(cpu, weight);
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return cpu;
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}
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let phys_devs = {};
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let netdev_phys = {};
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let netdevs = map(glob("/sys/class/net/*"), (dev) => basename(dev));
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for (let dev in netdevs) {
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let pdev_path = realpath(`/sys/class/net/${dev}/device`);
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if (!pdev_path)
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continue;
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if (length(glob(`/sys/class/net/${dev}/lower_*`)) > 0)
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continue;
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let pdev = phys_devs[pdev_path];
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if (!pdev) {
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pdev = phys_devs[pdev_path] = {
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path: pdev_path,
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driver: basename(readlink(`${pdev_path}/driver`)),
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netdev: [],
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phy: [],
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tasks: [],
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};
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}
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let phyidx = trim(readfile(`/sys/class/net/${dev}/phy80211/index`));
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if (phyidx != null) {
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let phy = `phy${phyidx}`;
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if (index(pdev.phy, phy) < 0)
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push(pdev.phy, phy);
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}
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push(pdev.netdev, dev);
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netdev_phys[dev] = pdev;
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}
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for (let path in glob("/proc/*/exe")) {
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readlink(path);
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if (error() != "No such file or directory")
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continue;
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let pid = basename(dirname(path));
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let name = task_name(pid);
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for (let devname in phys_devs) {
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let dev = phys_devs[devname];
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if (!task_device_match(name, dev))
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continue;
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push(dev.tasks, pid);
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break;
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}
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}
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function assign_dev_cpu(dev) {
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if (length(dev.tasks) > 0) {
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let cpu = dev.napi_cpu = get_next_cpu(napi_weight);
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for (let task in dev.tasks)
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set_task_cpu(task, cpu);
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}
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if (length(dev.netdev) > 0) {
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let cpu = dev.rx_cpu = get_next_cpu(rx_weight, dev.napi_cpu);
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for (let netdev in dev.netdev)
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set_netdev_cpu(netdev, cpu);
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}
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}
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// Assign ethernet devices first
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for (let devname in phys_devs) {
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let dev = phys_devs[devname];
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if (!length(dev.phy))
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assign_dev_cpu(dev);
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}
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// Add bias to avoid assigning other tasks to CPUs with ethernet NAPI
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for (let devname in phys_devs) {
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let dev = phys_devs[devname];
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if (!length(dev.tasks) || dev.napi_cpu == null)
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continue;
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cpu_add_weight(dev.napi_cpu, eth_bias);
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}
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// Assign WLAN devices
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for (let devname in phys_devs) {
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let dev = phys_devs[devname];
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if (length(dev.phy) > 0)
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assign_dev_cpu(dev);
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}
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if (debug > 1)
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warn(sprintf("devices: %.J\ncpus: %.J\n", phys_devs, cpus));
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