[LEDE-DEV] [PATCH v2] [base-files] dont change defaults for vm.min_free_kbytes on devices with <64MiB RAM

[Bastian Bittorf]

with 5c9cc7b7f8920944a413644e1c2ea23bfe655bcb we changed the default
value of 'vm.min_free_kbytes' from ~650 to 4096 kilobytes on 32MiB-RAM-devices.
This makes them hardly useable with a lot of OOM-crashes.

Change that and use 1024 kilobytes for 32MiB-RAM-devices.
For devices with more than 32MiB RAM we keep the behaviour / the values.

While we are at it, localize vars and read the memory without AWK/nonforking.

changes v1 -> v2: (suggestions from Felix Fietkau, Rafał Miłecki)
- keep -quiet option from sysctl
- use 1024 kilobyte on 32MiB-devices instead of the kernel default
- consistently use unit [MiB]
---
 package/base-files/files/etc/init.d/sysctl | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/package/base-files/files/etc/init.d/sysctl b/package/base-files/files/etc/init.d/sysctl
index a0daec0..7a16e01 100755
--- a/package/base-files/files/etc/init.d/sysctl
+++ b/package/base-files/files/etc/init.d/sysctl
@@ -4,16 +4,20 @@
 START=11
 
 set_vm_min_free() {
-	mem="$(grep MemTotal /proc/meminfo  | awk '{print $2}')"
-	if [ "$mem" -gt 65536 ]; then # 128M
+	local mem value
+
+	read -r _ mem _ </proc/meminfo
+
+	if   [ "$mem" -gt 65536 ]; then	# 128MiB
 		val=16384
-	elif [ "$mem" -gt 32768 ]; then # 64M
+	elif [ "$mem" -gt 32768 ]; then	# 64MiB
 		val=8192
-	elif [ "$mem" -gt 16384 ]; then # 32M
-		val=4096
+	elif [ "$mem" -gt 16384 ]; then	# 32MiB
+		val=1024
 	else
 		return
 	fi
+
 	sysctl -qw vm.min_free_kbytes="$val"
 }
 
-- 
2.7.4