netifd: rewrite packet steering script
authorFelix Fietkau <nbd@nbd.name>
Fri, 12 Apr 2024 19:51:50 +0000 (21:51 +0200)
committerFelix Fietkau <nbd@nbd.name>
Sun, 14 Apr 2024 14:24:37 +0000 (16:24 +0200)
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>
package/network/config/netifd/Makefile
package/network/config/netifd/files/etc/init.d/packet_steering
package/network/config/netifd/files/usr/libexec/network/packet-steering.sh [deleted file]
package/network/config/netifd/files/usr/libexec/network/packet-steering.uc [new file with mode: 0755]

index 35b5c0b2773deccf089eebc4e173b7adf5a9f4b0..d80c2eeed6bd35d1e3c970b69a2194d0c2826c06 100644 (file)
@@ -21,7 +21,7 @@ include $(INCLUDE_DIR)/cmake.mk
 define Package/netifd
   SECTION:=base
   CATEGORY:=Base system
-  DEPENDS:=+libuci +libnl-tiny +libubus +ubus +ubusd +jshn +libubox +libudebug
+  DEPENDS:=+libuci +libnl-tiny +libubus +ubus +ubusd +jshn +libubox +libudebug +ucode +ucode-mod-fs
   TITLE:=OpenWrt Network Interface Configuration Daemon
 endef
 
index 9d8f791e23b3059c23d6517f8f45953db41f4248..d6f6afc2e1b5322cb2d91357e228fcd77552087d 100755 (executable)
@@ -14,5 +14,10 @@ service_triggers() {
 }
 
 reload_service() {
-       /usr/libexec/network/packet-steering.sh
+       packet_steering="$(uci get "network.@globals[0].packet_steering")"
+       if [ -e "/usr/libexec/platform/packet-steering.sh" ]; then
+               /usr/libexec/platform/packet-steering.sh "$packet_steering"
+       else
+               /usr/libexec/network/packet-steering.uc "$packet_steering"
+       fi
 }
diff --git a/package/network/config/netifd/files/usr/libexec/network/packet-steering.sh b/package/network/config/netifd/files/usr/libexec/network/packet-steering.sh
deleted file mode 100755 (executable)
index 799c080..0000000
+++ /dev/null
@@ -1,70 +0,0 @@
-#!/bin/sh
-NPROCS="$(grep -c "^processor.*:" /proc/cpuinfo)"
-[ "$NPROCS" -gt 1 ] || exit
-
-PROC_MASK="$(( (1 << $NPROCS) - 1 ))"
-
-find_irq_cpu() {
-       local dev="$1"
-       local match="$(grep -m 1 "$dev\$" /proc/interrupts)"
-       local cpu=0
-
-       [ -n "$match" ] && {
-               set -- $match
-               shift
-               for cur in $(seq 1 $NPROCS); do
-                       [ "$1" -gt 0 ] && {
-                               cpu=$(($cur - 1))
-                               break
-                       }
-                       shift
-               done
-       }
-
-       echo "$cpu"
-}
-
-set_hex_val() {
-       local file="$1"
-       local val="$2"
-       val="$(printf %x "$val")"
-       [ -n "$DEBUG" ] && echo "$file = $val"
-       echo "$val" > "$file"
-}
-
-packet_steering="$(uci get "network.@globals[0].packet_steering")"
-[ "$packet_steering" != 1 ] && exit 0
-
-exec 512>/var/lock/smp_tune.lock
-flock 512 || exit 1
-
-[ -e "/usr/libexec/platform/packet-steering.sh" ] && {
-       /usr/libexec/platform/packet-steering.sh
-       exit 0
-}
-
-for dev in /sys/class/net/*; do
-       [ -d "$dev" ] || continue
-
-       # ignore virtual interfaces
-       [ -n "$(ls "${dev}/" | grep '^lower_')" ] && continue
-       [ -d "${dev}/device" ] || continue
-
-       device="$(readlink "${dev}/device")"
-       device="$(basename "$device")"
-       irq_cpu="$(find_irq_cpu "$device")"
-       irq_cpu_mask="$((1 << $irq_cpu))"
-
-       for q in ${dev}/queues/tx-*; do
-               set_hex_val "$q/xps_cpus" "$PROC_MASK"
-       done
-
-       # ignore dsa slave ports for RPS
-       subsys="$(readlink "${dev}/device/subsystem")"
-       subsys="$(basename "$subsys")"
-       [ "$subsys" = "mdio_bus" ] && continue
-
-       for q in ${dev}/queues/rx-*; do
-               set_hex_val "$q/rps_cpus" "$PROC_MASK"
-       done
-done
diff --git a/package/network/config/netifd/files/usr/libexec/network/packet-steering.uc b/package/network/config/netifd/files/usr/libexec/network/packet-steering.uc
new file mode 100755 (executable)
index 0000000..f146a96
--- /dev/null
@@ -0,0 +1,200 @@
+#!/usr/bin/env ucode
+'use strict';
+import { glob, basename, dirname, readlink, readfile, realpath, writefile, error, open } from "fs";
+
+let napi_weight = 1.0;
+let cpu_thread_weight = 0.75;
+let rx_weight = 0.75;
+let eth_bias = 2.0;
+let debug = 0, do_nothing = 0;
+let disable;
+let cpus;
+
+for (let arg in ARGV) {
+       switch (arg) {
+       case "-d":
+               debug++;
+               break;
+       case "-n":
+               do_nothing++;
+               break;
+       case '0':
+               disable = true;
+               break;
+       }
+}
+
+function task_name(pid)
+{
+       let stat = open(`/proc/${pid}/status`, "r");
+       let line = stat.read("line");
+       stat.close();
+       return trim(split(line, "\t", 2)[1]);
+}
+
+function set_task_cpu(pid, cpu) {
+       if (disable)
+               cpu = join(",", map(cpus, (cpu) => cpu.id));
+       if (debug || do_nothing)
+               warn(`taskset -p -c ${cpu} ${task_name(pid)}\n`);
+       if (!do_nothing)
+               system(`taskset -p -c ${cpu} ${pid}`);
+}
+
+function set_netdev_cpu(dev, cpu) {
+       let queues = glob(`/sys/class/net/${dev}/queues/rx-*/rps_cpus`);
+       let val = sprintf("%x", (1 << int(cpu)));
+       if (disable)
+               val = 0;
+       for (let queue in queues) {
+               if (debug || do_nothing)
+                       warn(`echo ${val} > ${queue}\n`);
+               if (!do_nothing)
+                       writefile(queue, `${val}`);
+       }
+}
+
+function task_device_match(name, device)
+{
+       let napi_match = match(name, /napi\/([^-+])-\d+/);
+       if (!napi_match)
+               napi_match = match(name, /mt76-tx (phy\d+)/);
+       if (napi_match &&
+           (index(device.phy, napi_match[1]) >= 0 ||
+            index(device.netdev, napi_match[1]) >= 0))
+               return true;
+
+       if (device.driver == "mtk_soc_eth" && match(name, /napi\/mtk_eth-/))
+               return true;
+
+       return false;
+}
+
+cpus = map(glob("/sys/bus/cpu/devices/*"), (path) => {
+       return {
+               id: int(match(path, /.*cpu(\d+)/)[1]),
+               core: int(trim(readfile(`${path}/topology/core_id`))),
+               load: 0.0,
+       };
+});
+
+cpus = slice(cpus, 0, 64);
+if (length(cpus) < 2)
+       exit(0);
+
+function cpu_add_weight(cpu_id, weight)
+{
+       let cpu = cpus[cpu_id];
+       cpu.load += weight;
+       for (let sibling in cpus) {
+               if (sibling == cpu || sibling.core != cpu.core)
+                       continue;
+               sibling.load += weight * cpu_thread_weight;
+       }
+}
+
+function get_next_cpu(weight, prev_cpu)
+{
+       if (disable)
+               return 0;
+
+       let sort_cpus = sort(slice(cpus), (a, b) => a.load - b.load);
+       let idx = 0;
+
+       if (prev_cpu != null && sort_cpus[idx].id == prev_cpu)
+               idx++;
+
+       let cpu = sort_cpus[idx].id;
+       cpu_add_weight(cpu, weight);
+       return cpu;
+}
+
+let phys_devs = {};
+let netdev_phys = {};
+let netdevs = map(glob("/sys/class/net/*"), (dev) => basename(dev));
+
+for (let dev in netdevs) {
+       let pdev_path = realpath(`/sys/class/net/${dev}/device`);
+       if (!pdev_path)
+               continue;
+
+       if (length(glob(`/sys/class/net/${dev}/lower_*`)) > 0)
+               continue;
+
+       let pdev = phys_devs[pdev_path];
+       if (!pdev) {
+               pdev = phys_devs[pdev_path] = {
+                       path: pdev_path,
+                       driver: basename(readlink(`${pdev_path}/driver`)),
+                       netdev: [],
+                       phy: [],
+                       tasks: [],
+               };
+       }
+
+       let phyidx = trim(readfile(`/sys/class/net/${dev}/phy80211/index`));
+       if (phyidx != null) {
+               let phy = `phy${phyidx}`;
+               if (index(pdev.phy, phy) < 0)
+                       push(pdev.phy, phy);
+       }
+
+       push(pdev.netdev, dev);
+       netdev_phys[dev] = pdev;
+}
+
+for (let path in glob("/proc/*/exe")) {
+       readlink(path);
+       if (error() != "No such file or directory")
+               continue;
+
+       let pid = basename(dirname(path));
+       let name = task_name(pid);
+       for (let devname in phys_devs) {
+               let dev = phys_devs[devname];
+               if (!task_device_match(name, dev))
+                       continue;
+
+               push(dev.tasks, pid);
+               break;
+       }
+}
+
+function assign_dev_cpu(dev) {
+       if (length(dev.tasks) > 0) {
+               let cpu = dev.napi_cpu = get_next_cpu(napi_weight);
+               for (let task in dev.tasks)
+                       set_task_cpu(task, cpu);
+       }
+
+       if (length(dev.netdev) > 0) {
+               let cpu = dev.rx_cpu = get_next_cpu(rx_weight, dev.napi_cpu);
+               for (let netdev in dev.netdev)
+                       set_netdev_cpu(netdev, cpu);
+       }
+}
+
+// Assign ethernet devices first
+for (let devname in phys_devs) {
+       let dev = phys_devs[devname];
+       if (!length(dev.phy))
+               assign_dev_cpu(dev);
+}
+
+// Add bias to avoid assigning other tasks to CPUs with ethernet NAPI
+for (let devname in phys_devs) {
+       let dev = phys_devs[devname];
+       if (!length(dev.tasks) || dev.napi_cpu == null)
+               continue;
+       cpu_add_weight(dev.napi_cpu, eth_bias);
+}
+
+// Assign WLAN devices
+for (let devname in phys_devs) {
+       let dev = phys_devs[devname];
+       if (length(dev.phy) > 0)
+               assign_dev_cpu(dev);
+}
+
+if (debug > 1)
+       warn(sprintf("devices: %.J\ncpus: %.J\n", phys_devs, cpus));