From 2dcb59d43fce8a881e168a7e33b01bf53d96679d Mon Sep 17 00:00:00 2001
From: Stefan Agner <stefan@agner.ch>
Date: Fri, 31 Mar 2023 23:28:43 +0200
Subject: [PATCH] Enable Multi-Gen LRU (#2392)

* Enable Multi-Gen LRU

Multi-Gen LRU should improve performance under memory pressure. This is
especially useful for embedded platforms where memory is scarce.

* Add service to configure Multi-Gen LRU

Use min_ttl_ms of 1 which is the least aggressive in terms of lag. Since
we are a server application, we can tune trashing prevention with a
higher acceptable lag.
---
 buildroot-external/kernel/hassos.config               |  2 +-
 .../usr/lib/systemd/system/haos-mglru.service         | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 buildroot-external/rootfs-overlay/usr/lib/systemd/system/haos-mglru.service

diff --git a/buildroot-external/kernel/hassos.config b/buildroot-external/kernel/hassos.config
index 10847f220..6518f149e 100644
--- a/buildroot-external/kernel/hassos.config
+++ b/buildroot-external/kernel/hassos.config
@@ -15,7 +15,7 @@ CONFIG_ZSWAP_ZPOOL_DEFAULT_ZSMALLOC=y
 CONFIG_ZSMALLOC=y
 
 CONFIG_LRU_GEN=y
-# CONFIG_LRU_GEN_ENABLED is not set
+CONFIG_LRU_GEN_ENABLED=y
 
 CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND=y
 
diff --git a/buildroot-external/rootfs-overlay/usr/lib/systemd/system/haos-mglru.service b/buildroot-external/rootfs-overlay/usr/lib/systemd/system/haos-mglru.service
new file mode 100644
index 000000000..2f3206977
--- /dev/null
+++ b/buildroot-external/rootfs-overlay/usr/lib/systemd/system/haos-mglru.service
@@ -0,0 +1,11 @@
+[Unit]
+Description=Configure multigenerational LRU
+ConditionPathExists=/sys/kernel/mm/lru_gen/enabled
+
+[Service]
+Type=oneshot
+
+ExecStart=/bin/sh -c "echo 1 > /sys/kernel/mm/lru_gen/min_ttl_ms"
+
+[Install]
+WantedBy=basic.target