From 0f24d3c67fa6e9feedd486850e51691303060b09 Mon Sep 17 00:00:00 2001
From: Jonathan Bauer
Date: Fri, 9 Jul 2021 17:07:28 +0200
Subject: [zram-swap] move zram-swap to its own module

---
 .../system/sysinit.target.wants/zram-swap.service  |   1 +
 .../data/etc/systemd/system/zram-swap.service      |  10 ++
 .../data/opt/openslx/scripts/systemd-zram_swap     | 115 +++++++++++++++++++++
 3 files changed, 126 insertions(+)
 create mode 120000 core/modules/zram-swap/data/etc/systemd/system/sysinit.target.wants/zram-swap.service
 create mode 100644 core/modules/zram-swap/data/etc/systemd/system/zram-swap.service
 create mode 100755 core/modules/zram-swap/data/opt/openslx/scripts/systemd-zram_swap

(limited to 'core/modules/zram-swap')

diff --git a/core/modules/zram-swap/data/etc/systemd/system/sysinit.target.wants/zram-swap.service b/core/modules/zram-swap/data/etc/systemd/system/sysinit.target.wants/zram-swap.service
new file mode 120000
index 00000000..c1754b11
--- /dev/null
+++ b/core/modules/zram-swap/data/etc/systemd/system/sysinit.target.wants/zram-swap.service
@@ -0,0 +1 @@
+../zram-swap.service
\ No newline at end of file
diff --git a/core/modules/zram-swap/data/etc/systemd/system/zram-swap.service b/core/modules/zram-swap/data/etc/systemd/system/zram-swap.service
new file mode 100644
index 00000000..a458b380
--- /dev/null
+++ b/core/modules/zram-swap/data/etc/systemd/system/zram-swap.service
@@ -0,0 +1,10 @@
+[Unit]
+Description=Setup zram swap partitions
+DefaultDependencies=no
+Wants=swap.target
+Before=swap.target
+
+[Service]
+Type=oneshot
+ExecStart=/opt/openslx/scripts/systemd-zram_swap
+RemainAfterExit=yes
diff --git a/core/modules/zram-swap/data/opt/openslx/scripts/systemd-zram_swap b/core/modules/zram-swap/data/opt/openslx/scripts/systemd-zram_swap
new file mode 100755
index 00000000..413ce215
--- /dev/null
+++ b/core/modules/zram-swap/data/opt/openslx/scripts/systemd-zram_swap
@@ -0,0 +1,115 @@
+#!/bin/ash
+# -----------------------------------------------------------------------------
+#
+# Copyright (c) 2013..2018 bwLehrpool-Projektteam
+#
+# This program/file is free software distributed under the GPL version 2.
+# See https://www.gnu.org/licenses/old-licenses/gpl-2.0-standalone.html
+#
+# If you have any feedback please consult https://bwlehrpool.de and
+# send your feedback to support@bwlehrpool.de.
+#
+# General information about bwLehrpool can be found at https://bwlehrpool.de
+#
+# -----------------------------------------------------------------------------
+#
+# Local hard disk autodetection script for OpenSLX linux stateless clients,
+# detecting swap and special partitions
+
+#############################################################################
+
+
+# Add zram swap
+# Some older ubuntu kernels had a problem here, see https://bugs.launchpad.net/ubuntu/+source/linux-lts-raring/+bug/1217189
+# So make sure you're up to date
+
+make_swap () {
+	[ $# -ne 3 ] && echo "make_swap: Wrong parameter count $#" && return 1
+	local USE="$1"
+	local DEV="$2"
+	local STREAMS="$3"
+	echo "$USE" > "/sys/block/zram${DEV}/disksize" || return 1
+	[ -n "$STREAMS" ] && echo "$STREAMS" > "/sys/block/zram${DEV}/max_comp_streams"
+	(
+		mkswap "/dev/zram${DEV}"
+		swapon "/dev/zram${DEV}" -p 1000 # high priority (in case we have hdd swap 0x82, prefer zram)
+	) &
+}
+
+# Count physical CPUs
+CPUS=$(cat /sys/devices/system/cpu/cpu*/topology/thread_siblings_list | sort -u | wc -l) # cat for *
+if [ -z "$CPUS" ]; then
+	echo "ERROR: Could not determine CPU core count"
+else
+	CPUS=1
+fi
+
+KERN=$(uname -r)
+if [ "${KERN%%.*}" -le 4 ]; then
+	DEVS=$CPUS
+	[ "$DEVS" -gt "16" ] && DEVS=16 # zram can only handle up to 32 devices, the system can apparently even just handle 29 swap partitions, so use a reasonable upper limit
+	STREAMS=
+else
+	DEVS=1
+	STREAMS=$CPUS
+fi
+
+if [ -e "/sys/class/zram-control/hot_add" ]; then
+	: # nothing to do, loaded and hot_add available
+elif ! modprobe zram "num_devices=$DEVS"; then
+	echo "ERROR: Could not load zram module"
+	exit 1
+fi
+
+TOTAL=$(grep ^MemTotal /proc/meminfo | awk '{print $2}')
+USE=$(( TOTAL / ( 2 * DEVS ) ))
+echo "Have $CPUS cores, $TOTAL kb mem, use $USE kb zram swap each for $DEVS devices."
+USE=$(( USE * 1024 ))
+DEV=0
+NUM=0
+FAILS=0
+while [ "$NUM" -lt "$DEVS" ]; do
+	if [ -e "/sys/block/zram${DEV}" ]; then
+		if ! [ -e "/sys/block/zram${DEV}/initstate" ] || [ "$(cat "/sys/block/zram${DEV}/initstate")" = 0 ]; then
+			if make_swap "$USE" "$DEV" "$STREAMS"; then
+				NUM=$(( NUM + 1 ))
+			fi
+		fi
+		DEV=$(( DEV + 1 ))
+	elif [ -e "/sys/class/zram-control/hot_add" ]; then
+		DEV=$(cat /sys/class/zram-control/hot_add)
+		if [ -z "$DEV" ]; then
+			echo "ERROR: Cannot hot_add another zram device"
+			break
+		fi
+		if make_swap "$USE" "$DEV" "$STREAMS"; then
+			NUM=$(( NUM + 1 ))
+		else
+			FAILS=$(( FAILS + 1 ))
+			if [ "$FAILS" -gt 4 ]; then
+				echo "ERROR: Could not swap on hot added device -- giving up"
+				break
+			fi
+		fi
+		DEV=$(( DEV + 1 ))
+	else
+		echo "ERROR: Cannot add another zram device: No hot_add support"
+		break
+	fi
+done
+
+# Increase min free memory so we have enough mem available when trying to move
+# something to zram swap. We want 1%, or at least 64MiB
+CURRENT=$(cat "/proc/sys/vm/min_free_kbytes")
+TOTAL=$(awk '{ if ($1 == "MemTotal:") { print $2; exit } }' /proc/meminfo)
+WANT=$(( TOTAL / 100 ))
+[ "$WANT" -gt 65535 ] || WANT=65535 # minimum 64M
+if [ "$CURRENT" -lt "$WANT" ]; then
+	echo "$WANT" > "/proc/sys/vm/min_free_kbytes"
+fi
+
+# Wait, so we don't trigger swap.target too early
+wait
+
+exit 0
+
-- 
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