From a50f5b3fb2024fe00f726dff2093a83410bd3c8d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Fri, 10 Jun 2022 10:51:23 +0200
Subject: [PATCH] bcm53xx: enable & setup packet steering
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Packet steering can improve NAT masquarade performance on Northstar by
40-50%. It makes reaching 940-942 Mb/s possible on BCM4708 (and
obviously BCM47094 too). Add scripts setting up the most optimal
Northstar setup.

Below are testing results for running iperf TCP traffic from LAN to WAN.
They were used to pick up golden values.

┌──────────┬──────────┬────────────────────┬────────────────────┐
│   eth0   │  br-lan  │ flow_offloading=0  │ flow_offloading=1  │
│          │          ├─────────┬──────────┼─────────┬──────────┤
│ rps_cpus │ rps_cpus │ BCM4708 │ BCM47094 │ BCM4708 │ BCM47094 │
├──────────┼──────────┼─────────┼──────────┼─────────┼──────────┤
│        0 │        0 │     387 │      671 │     707 │      941 │
│        0 │        1 │     343 │      576 │     705 │      941 │
│        0 │        2 │   ✓ 574 │    ✓ 941 │     704 │      940 │
│        1 │        0 │     320 │      549 │     561 │      941 │
│        1 │        1 │     327 │      551 │     553 │      941 │
│        1 │        2 │     523 │    ✓ 940 │     559 │      940 │
│        2 │        0 │     383 │      652 │   ✓ 940 │      941 │
│        2 │        1 │     448 │      754 │   ✓ 942 │      941 │
│        2 │        2 │     404 │      655 │   ✓ 941 │      941 │
└──────────┴──────────┴─────────┴──────────┴─────────┴──────────┘

Above tests were performed with all eth0 interrupts handled by CPU0.
Setting "echo 2 > /proc/irq/38/smp_affinity" was tested on BCM4708 but
it didn't increased speeds (just required different steering):

┌──────────┬──────────┬───────────┐
│   eth0   │  br-lan  │ flow_offl │
│   rx-0   │   rx-0   │ oading=0  │
│ rps_cpus │ rps_cpus │  BCM4708  │
├──────────┼──────────┼───────────┤
│        0 │        0 │       384 │
│        0 │        1 │     ✓ 574 │
│        0 │        2 │       348 │
│        1 │        0 │       383 │
│        1 │        1 │       412 │
│        1 │        2 │       448 │
│        2 │        0 │       321 │
│        2 │        1 │       520 │
│        2 │        2 │       327 │
└──────────┴──────────┴───────────┘

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
(cherry picked from commit fcbd39689ebfef20c62fe3882d51f3af765e8028)
---
 .../bcm53xx/base-files/etc/init.d/fastnetwork | 44 +++++++++++++++++++
 .../etc/uci-defaults/05_packet_steering       |  3 ++
 2 files changed, 47 insertions(+)
 create mode 100755 target/linux/bcm53xx/base-files/etc/init.d/fastnetwork
 create mode 100644 target/linux/bcm53xx/base-files/etc/uci-defaults/05_packet_steering

diff --git a/target/linux/bcm53xx/base-files/etc/init.d/fastnetwork b/target/linux/bcm53xx/base-files/etc/init.d/fastnetwork
new file mode 100755
index 0000000000..1999d13707
--- /dev/null
+++ b/target/linux/bcm53xx/base-files/etc/init.d/fastnetwork
@@ -0,0 +1,44 @@
+#!/bin/sh /etc/rc.common
+
+START=25
+USE_PROCD=1
+
+start_service() {
+	reload_service
+}
+
+service_triggers() {
+	procd_add_reload_trigger "network"
+	procd_add_reload_trigger "firewall"
+	procd_add_reload_interface_trigger "lan"
+}
+
+reload_service() {
+	local packet_steering="$(uci -q get network.@globals[0].packet_steering)"
+	local num_cpus="$(grep -c "^processor.*:" /proc/cpuinfo)"
+	local flow_offloading="$(uci -q get firewall.@defaults[0].flow_offloading)"
+	local flow_offloading_hw="$(uci -q get firewall.@defaults[0].flow_offloading_hw)"
+
+	# Any steering on 1 CPU (BCM47081) worsens network performance
+	[ "$num_cpus" != 2 ] && return
+
+	[ "$packet_steering" != 1 ] && {
+		echo 0 > /sys/class/net/br-lan/queues/rx-0/rps_cpus
+		echo 0 > /sys/class/net/eth0/queues/rx-0/rps_cpus
+		return
+	}
+
+	if [ ${flow_offloading_hw:-0} -gt 0 ]; then
+		# HW offloading
+		echo 0 > /sys/class/net/br-lan/queues/rx-0/rps_cpus
+		echo 0 > /sys/class/net/eth0/queues/rx-0/rps_cpus
+	elif [ ${flow_offloading:-0} -gt 0 ]; then
+		# SW offloading
+		# br-lan setup doesn't seem to matter for offloading case
+		echo 2 > /sys/class/net/eth0/queues/rx-0/rps_cpus
+	else
+		# Default
+		echo 2 > /sys/class/net/br-lan/queues/rx-0/rps_cpus
+		echo 0 > /sys/class/net/eth0/queues/rx-0/rps_cpus
+	fi
+}
diff --git a/target/linux/bcm53xx/base-files/etc/uci-defaults/05_packet_steering b/target/linux/bcm53xx/base-files/etc/uci-defaults/05_packet_steering
new file mode 100644
index 0000000000..98c9497815
--- /dev/null
+++ b/target/linux/bcm53xx/base-files/etc/uci-defaults/05_packet_steering
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+uci set network.@globals[0].packet_steering="1"